double byte - Page 63 - Developer IT

Would this union work if char had stricter alignment requirements than int?

- by paxdiablo

Recently I came across the following snippet, which is an attempt to ensure all bytes of i (nad no more) are accessible as individual elements of c: union { int i; char c[sizeof(int)]; }; Now this seems a good idea, but I wonder if the standard allows for the case where the alignment requirements for char are more restrictive than that for int. In other words, is it possible to have a four-byte int which is required to be aligned on a four-byte boundary with a one-byte char (it is one byte, by definition, see below) required to be aligned on a sixteen-byte boundary? And would this stuff up the use of the union above? Two things to note. I'm talking specifically about what the standard allows here, not what a sane implementor/architecture would provide. I'm using the term "byte" in the ISO C sense, where it's the width of a char, not necessarily 8 bits.

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Problem with a recursive function to find sqrt of a number

- by Eternal Learner

Below is a simple program which computes sqrt of a number using Bisection. While executing this with a call like sqrtr(4,1,4) in goes into an endless recursion . I am unable to figure out why this is happening. Below is the function : double sqrtr(double N , double Low ,double High ) { double value = 0.00; double mid = (Low + High + 1)/2; if(Low == High) { value = High; } else if (N < mid * mid ) { value = sqrtr(N,Low,mid-1) ; } else if(N >= mid * mid) { value = sqrtr(N,mid,High) ; } return value; }

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Compiler error while compiling the RAPID library on VS2008

- by Demi

I've downloaded the RAPID library and tried to compile it on Microsoft Visual Studio 2008. However, I'm getting the following compiler error: C4430 missing type specifier - int assumed. Note: C++ does not support default-int at this code segment (the exact line that produces the error is int flag): class RAPID_model { public: box *b; int num_boxes_alloced; tri *tris; int num_tris; int num_tris_alloced; int build_state; int build_hierarchy(); friend RAPID_Collide(double R1[3][3], double T1[3], double s1, RAPID_model *RAPID_model1, double R2[3][3], double T2[3], double s2, RAPID_model *RAPID_model2, int flag); Can anyone please help me with this? Thank you

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Why won't this static_cast in C++ work?

- by samoz

When I try to use a static_cast to cast a double* to an int*, I get the following error: invalid static_cast from type ‘double*’ to type ‘int*’ Here is the code: #include <iostream> int main() { double* p = new double(2); int* r; r=static_cast<int*>(p); std::cout << *r << std::endl; } I understand that there would be problems converting between a double and an int, but why is there a problem converting between a double* and an int*?

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Is this valid Java code?

- by Eric

I'm using Eclipse, and it is perfectly happy with the following code: public interface MessageType { public static final byte KICK = 0x01; public static final byte US_PING = 0x02; public static final byte GOAL_POS = 0x04; public static final byte SHUTDOWN = 0x08; public static final byte[] MESSAGES = new byte[] { KICK, US_PING, GOAL_POS, SHUTDOWN }; } public class MessageTest implements MessageType { public static void main(String[] args) { int b = MessageType.MESSAGES.length; //Not happy } } However, the platform that I'm running it on crashes at the line marked above. By crash, think an equivalent of a BSOD. Is there anything wrong with my code, or do I need to pursue the developers of the Java VM for my platform?

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Not seeing Sync Block in Object Layout

- by bob-bedell

It's my understanding the all .NET object instances begin with an 8 byte 'object header': a synch block (4 byte pointer into a SynchTableEntry table), and a type handle (4 byte pointer into the types method table). I'm not seeing this in VS 2010 RC's (CLR 4.0) debugger memory windows. Here's a simple class that will generate a 16 byte instance, less the object header. class Program { short myInt = 2; // 4 bytes long myLong = 3; // 8 bytes string myString = "aString"; // 4 byte object reference // 16 byte instance static void Main(string[] args) { new Program(); return; } } An SOS object dump tells me that the total object size is 24 bytes. That makes sense. My 16 byte instance plus an 8 byte object header. !DumpObj 0205b660 Name: Offset_Test.Program MethodTable: 000d383c EEClass: 000d13f8 Size: 24(0x18) bytes File: C:\Users\Bob\Desktop\Offset_Test\Offset_Test\bin\Debug\Offset_Test.exe Fields: MT Field Offset Type VT Attr Value Name 632020fc 4000001 10 System.Int16 1 instance 2 myInt 632050d8 4000002 4 System.Int64 1 instance 3 myLong 631fd2b8 4000003 c System.String 0 instance 0205b678 myString Here's the raw memory: 0x0205B660 000d383c 00000003 00000000 0205b678 00000002 ... And here are some annotations: offset 0 000d383c ;TypeHandle (pointer to MethodTable), 4 bytes offset 4 00000003 00000000 ;myLong, 8 bytes offset 12 0205b678 ;myString, 4 byte reference to address of "myString" on GC Heap offset 16 00000002 ;myInt, 4 bytes My object begins a address 0x0205B660. But I can only account for 20 bytes of it, the type handle and the instance fields. There is no sign of a synch block pointer. The object size is reported as 24 bytes, but the debugger is showing that it only occupies 20 bytes of memory. I'm reading Drill Into .NET Framework Internals to See How the CLR Creates Runtime Objects, and expected the first 4 bytes of my object to be a zeroed synch block pointer, as shown in Figure 8 of that article. Granted, this is an article about CLR 1.1. I'm just wondering if the difference between what I'm seeing and what this early article reports is a change in either the debugger's display of object layout, or in the way the CLR lays out objects in versions later than 1.1. Anyway, can anyone account for my 4 missing bytes?

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Linkage of namespace functions

- by user144182

I have a couple of methods declared at the namespace level within a header for a class: // MyClass.h namespace network { int Method1(double d); int Method2(double d); class MyClass { //... } } then defined in //MyClass.cpp int Method1(double d) { ... } int Method2(double d) { ... } This project compiles cleanly and is a dependency for a ui project which uses MyClass. The functions were previously member functions of MyClass, but were moved to namespace since it was more appropriate. My problem is the ui project complains when it gets to the linker: 1network.lib(MyClass.obj) : error LNK2001: unresolved external symbol "int __cdecl network::Method1(double)" (?INT@ds@sim@@YAHN@Z) 1network.lib(MyClass.obj) : error LNK2001: unresolved external symbol "int __cdecl network::Method2(double)" (?CINT@ds@sim@@YAHN@Z) What am I doing wrong?

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Intersection between sets containing different types of variables

- by Gacek

Let's assume we have two collections: List<double> values List<SomePoint> points where SomePoint is a type containing three coordinates of the point: SomePoint { double X; double Y; double Z; } Now, I would like to perform the intersection between these two collections to find out for which points in points the z coordinate is eqal to one of the elements of values I created something like that: HashSet<double> hash = new HashSet<double>(points.Select(p=>p.Z)); hash.IntersectWith(values); var result = new List<SomePoints>(); foreach(var h in hash) result.Add(points.Find(p => p.Z == h)); But it won't return these points for which there is the same Z value, but different X and Y. Is there any better way to do it?

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excplicitly casting constness in

- by jimifiki

With the following code void TestF(const double ** testv){;} void callTest(){ double** test; TestF(test); } I get this: error C2664: 'TestF' : cannot convert parameter 1 from 'double **' to 'const double **' I cannot understand why. Why test cannot be silently casted to const double**? Why should I do it explicitly? I know that TestF(const_cast<const double**>(test)) makes my code correct, but I feel this should be unnecessary. Are there some key concepts about const that I'm missing?

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C# Making private instance variable accesable (jagged array)

- by Chris

Hello, In a attempt to put some more oop in a program i am looking to make a private instance variable in one class (object) accesable to a class. private byte [][] J; All those code refers to this jagged array with this. Now in the other class i putted all the for loops along with the consolewritlines to display the wanted results. Basicly it says "the name J does not exist in the current context" But how exactly do i make this J accesable? I have tried with get and set but i keep getting 'cannot convert to byte to byte[][]' Also what kind of cyntax would i need with get and set? Something along like this? Or would i need several more steps? : public Byte JArray get { return J; } //can converrt to byte here set { J = value; } //cannnot convert to byte here Kind regards

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Where to declare variable? C#

- by user1303781

I am trying to make an average function... 'Total' adds them, then 'Total' is divided by n, the number of entries... No matter where I put 'double Total;', I get an error message. In this example I get... Use of unassigned local variable 'Total' If I put it before the comment, both references show up as error... I'm sure it's something simple..... namespace frmAssignment3 { class StatisticalFunctions { public static class Statistics { //public static double Average(List<MachineData.MachineRecord> argMachineDataList) public static double Average(List<double> argMachineDataList) { double Total; int n; for (n = 1; n <= argMachineDataList.Count; n++) { Total = argMachineDataList[n]; } return Total / n; } public static double StDevSample(List<MachineData.MachineRecord> argMachineDataList) { return -1; } } } }

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Comparing char for validation in C++

- by Corey Starbird

/* PROGRAM: Ch6_14.cpp Written by Corey Starbird This program calculates the balance owed to a hospital for a patient. Last modified: 10/28/13 */ #include <iostream> #include <fstream> #include <iomanip> #include <string> using namespace std; // Prototypes for In-patient and Out-patient functions. double stayTotal (int, double, double, double); // For In-patients double stayTotal (double, double); // For Out-patients int main() { char patientType; // In-patient (I or i) or Out-patient (O or o) double rate, // Daily rate for the In-patient stay servCharge, // Service charge for the stay medCharge, // Medication charge for the stay inTotal, // Total for the In-patient stay outTotal; // Total for the Out-patient stay int days; // Number of days for the In-patient stay // Find out if they were an In-patient or an Out-patient cout << "Welcome, please enter (I) for an In-patient or (O) for an Out-patient:" << endl; cin >> patientType; while (patientType != 'I' || 'i' || 'O' || 'o') { cout << "Invalid entry. Please enter either (I) for an In-patient or (O) for an Out-patient:" << endl; cin >> patientType; } cout << "FIN"; return 0; } Hey, brand new to C++ here. I am working on a project and I'm having trouble figuring out why my validation for patientTypeisn't working properly. I first had double quotes, but realized that would denote strings. I changed them to single quotes, my program will compile and run now, but the while loop runs no matter what I enter, I, i, O, o, or anything else. I don't know why the while loop isn't checking the condition, seeing that I did enter one of the characters in the condition, and move on to cout. Probably a simple mistake, but I thank you in advance.

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ASP.NET Podcast Show #148 - ASP.NET WebForms to build a Mobile Web Application

- by Wallym

Check the podcast site for the original url. This is the video and source code for an ASP.NET WebForms app that I wrote that is optimized for the iPhone and mobile environments. Subscribe to everything. Subscribe to WMV. Subscribe to M4V for iPhone/iPad. Subscribe to MP3. Download WMV. Download M4V for iPhone/iPad. Download MP3. Link to iWebKit. Source Code: <%@ Page Title="MapSplore" Language="C#" MasterPageFile="iPhoneMaster.master" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="AT_iPhone_Default" %> <asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server"></asp:Content><asp:Content ID="Content2" ContentPlaceHolderID="Content" Runat="Server" ClientIDMode="Static"> <asp:ScriptManager ID="sm" runat="server" EnablePartialRendering="true" EnableHistory="false" EnableCdn="true" /> <script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=true"></script> <script language="javascript" type="text/javascript">  </script> <asp:HiddenField ID="Latitude" runat="server" /> <asp:HiddenField ID="Longitude" runat="server" /> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js%22%3E%3C/script> <script language="javascript" type="text/javascript"> $(document).ready(function () { GetLocation(); setupMapDiv(); setupPlaceIveBeen(); }); function GetLocation() { if (navigator.geolocation != null) { navigator.geolocation.getCurrentPosition(getData); } else { var mess = document.getElementById('<%=Message.ClientID %>'); mess.innerHTML = "Sorry, your browser does not support geolocation. " + "Try the latest version of Safari on the iPhone, Android browser, or the latest version of FireFox."; } } function UpdateLocation_Click() { GetLocation(); } function getData(position) { var latitude = position.coords.latitude; var longitude = position.coords.longitude; var hdLat = document.getElementById('<%=Latitude.ClientID %>'); var hdLon = document.getElementById('<%=Longitude.ClientID %>'); hdLat.value = latitude; hdLon.value = longitude; } </script> <asp:Label ID="Message" runat="server" /> <asp:UpdatePanel ID="upl" runat="server"> <ContentTemplate> <asp:Panel ID="pnlStart" runat="server" Visible="true"> <div id="topbar"> <div id="title">MapSplore</div> </div> <div id="content"> <ul class="pageitem"> <li class="menu"> <asp:LinkButton ID="lbLocalDeals" runat="server" onclick="lbLocalDeals_Click"> <asp:Image ID="imLocalDeals" runat="server" ImageUrl="~/Images/ArtFavor_Money_Bag_Icon.png" Height="30" /> <span class="name">Local Deals.</span> <span class="arrow"></span> </asp:LinkButton> </li> <li class="menu"> <asp:LinkButton ID="lbLocalPlaces" runat="server" onclick="lbLocalPlaces_Click"> <asp:Image ID="imLocalPlaces" runat="server" ImageUrl="~/Images/Andy_Houses_on_the_horizon_-_Starburst_remix.png" Height="30" /> <span class="name">Local Places.</span> <span class="arrow"></span> </asp:LinkButton> </li> <li class="menu"> <asp:LinkButton ID="lbWhereIveBeen" runat="server" onclick="lbWhereIveBeen_Click"> <asp:Image ID="imImHere" runat="server" ImageUrl="~/Images/ryanlerch_flagpole.png" Height="30" /> <span class="name">I've been here.</span> <span class="arrow"></span> </asp:LinkButton> </li> <li class="menu"> <asp:LinkButton ID="lbMyStats" runat="server"> <asp:Image ID="imMyStats" runat="server" ImageUrl="~/Images/Anonymous_Spreadsheet.png" Height="30" /> <span class="name">My Stats.</span> <span class="arrow"></span> </asp:LinkButton> </li> <li class="menu"> <asp:LinkButton ID="lbAddAPlace" runat="server" onclick="lbAddAPlace_Click"> <asp:Image ID="imAddAPlace" runat="server" ImageUrl="~/Images/jean_victor_balin_add.png" Height="30" /> <span class="name">Add a Place.</span> <span class="arrow"></span> </asp:LinkButton> </li> <li class="button"> <input type="button" value="Update Your Current Location" onclick="UpdateLocation_Click()"> </li> </ul> </div> </asp:Panel> <div> <asp:Panel ID="pnlCoupons" runat="server" Visible="false"> <div id="topbar"> <div id="title">MapSplore</div> <div id="leftbutton"> <asp:LinkButton runat="server" Text="Return" ID="ReturnFromDeals" OnClick="ReturnFromDeals_Click" /></div></div> <div class="content"> <asp:ListView ID="lvCoupons" runat="server"> <LayoutTemplate> <ul class="pageitem" runat="server"> <asp:PlaceHolder ID="itemPlaceholder" runat="server" /> </ul> </LayoutTemplate> <ItemTemplate> <li class="menu"> <asp:LinkButton ID="lbBusiness" runat="server" Text='<%#Eval("Place.Name") %>' OnClick="lbBusiness_Click"> <span class="comment"> <asp:Label ID="lblAddress" runat="server" Text='<%#Eval("Place.Address1") %>' /> <asp:Label ID="lblDis" runat="server" Text='<%# Convert.ToString(Convert.ToInt32(Eval("Place.Distance"))) + " meters" %>' CssClass="smallText" /> <asp:HiddenField ID="hdPlaceId" runat="server" Value='<%#Eval("PlaceId") %>' /> <asp:HiddenField ID="hdGeoPromotionId" runat="server" Value='<%#Eval("GeoPromotionId") %>' /> </span> <span class="arrow"></span> </asp:LinkButton></li></ItemTemplate></asp:ListView><asp:GridView ID="gvCoupons" runat="server" AutoGenerateColumns="false"> <HeaderStyle BackColor="Silver" /> <AlternatingRowStyle BackColor="Wheat" /> <Columns> <asp:TemplateField AccessibleHeaderText="Business" HeaderText="Business"> <ItemTemplate> <asp:Image ID="imPlaceType" runat="server" Text='<%#Eval("Type") %>' ImageUrl='<%#Eval("Image") %>' /> <asp:LinkButton ID="lbBusiness" runat="server" Text='<%#Eval("Name") %>' OnClick="lbBusiness_Click" /> <asp:LinkButton ID="lblAddress" runat="server" Text='<%#Eval("Address1") %>' CssClass="smallText" /> <asp:Label ID="lblDis" runat="server" Text='<%# Convert.ToString(Convert.ToInt32(Eval("Distance"))) + " meters" %>' CssClass="smallText" /> <asp:HiddenField ID="hdPlaceId" runat="server" Value='<%#Eval("PlaceId") %>' /> <asp:HiddenField ID="hdGeoPromotionId" runat="server" Value='<%#Eval("GeoPromotionId") %>' /> <asp:Label ID="lblInfo" runat="server" Visible="false" /> </ItemTemplate> </asp:TemplateField> </Columns> </asp:GridView> </div> </asp:Panel> <asp:Panel ID="pnlPlaces" runat="server" Visible="false"> <div id="topbar"> <div id="title"> MapSplore</div><div id="leftbutton"> <asp:LinkButton runat="server" Text="Return" ID="ReturnFromPlaces" OnClick="ReturnFromPlaces_Click" /></div></div> <div id="content"> <asp:ListView ID="lvPlaces" runat="server"> <LayoutTemplate> <ul id="ulPlaces" class="pageitem" runat="server"> <asp:PlaceHolder ID="itemPlaceholder" runat="server" /> <li class="menu"> <asp:LinkButton ID="lbNotListed" runat="server" CssClass="name" OnClick="lbNotListed_Click"> Place not listed <span class="arrow"></span> </asp:LinkButton> </li> </ul> </LayoutTemplate> <ItemTemplate> <li class="menu"> <asp:LinkButton ID="lbImHere" runat="server" CssClass="name" OnClick="lbImHere_Click"> <%#DisplayName(Eval("Name")) %>  <%# Convert.ToString(Convert.ToInt32(Eval("Distance"))) + " meters" %> <asp:HiddenField ID="hdPlaceId" runat="server" Value='<%#Eval("PlaceId") %>' /> <span class="arrow"></span> </asp:LinkButton></li></ItemTemplate></asp:ListView> </div> </asp:Panel> <asp:Panel ID="pnlImHereNow" runat="server" Visible="false"> <div id="topbar"> <div id="title"> MapSplore</div><div id="leftbutton"> <asp:LinkButton runat="server" Text="Places" ID="lbImHereNowReturn" OnClick="lbImHereNowReturn_Click" /></div></div> <div id="rightbutton"> <asp:LinkButton runat="server" Text="Beginning" ID="lbBackToBeginning" OnClick="lbBackToBeginning_Click" /> </div> <div id="content"> <ul class="pageitem"> <asp:HiddenField ID="hdPlaceId" runat="server" /> <asp:HiddenField ID="hdPlaceLat" runat="server" /> <asp:HiddenField ID="hdPlaceLon" runat="server" /> <asp:HiddenField ID="hdPlaceTitle" runat="server" /> <asp:Button ID="btnImHereNow" runat="server" Text="I'm here" OnClick="btnImHereNow_Click" /> <asp:Label ID="lblPlaceTitle" runat="server" /><br /> <asp:TextBox ID="txtWhatsHappening" runat="server" TextMode="MultiLine" Rows="2" style="width:300px" /><br /> <div id="divImHere" style="width:300px; height:300px"></div> </div> </ul> </asp:Panel> <asp:Panel runat="server" ID="pnlIveBeenHere" Visible="false"> <div id="topbar"> <div id="title"> Where I've been</div><div id="leftbutton"> <asp:LinkButton ID="lbIveBeenHereBack" runat="server" Text="Back" OnClick="lbIveBeenHereBack_Click" /></div></div> <div id="content"> <asp:ListView ID="lvWhereIveBeen" runat="server"> <LayoutTemplate> <ul id="ulWhereIveBeen" class="pageitem" runat="server"> <asp:PlaceHolder ID="itemPlaceholder" runat="server" /> </ul> </LayoutTemplate> <ItemTemplate> <li class="menu" runat="server"> <asp:LinkButton ID="lbPlaceIveBeen" runat="server" OnClick="lbPlaceIveBeen_Click" CssClass="name"> <asp:Label ID="lblPlace" runat="server" Text='<%#Eval("PlaceName") %>' /> at <asp:Label ID="lblTime" runat="server" Text='<%#Eval("ATTime") %>' CssClass="content" /> <asp:HiddenField ID="hdATID" runat="server" Value='<%#Eval("ATID") %>' /> <span class="arrow"></span> </asp:LinkButton> </li> </ItemTemplate> </asp:ListView> </div> </asp:Panel> <asp:Panel runat="server" ID="pnlPlaceIveBeen" Visible="false"> <div id="topbar"> <div id="title"> I've been here </div> <div id="leftbutton"> <asp:LinkButton ID="lbPlaceIveBeenBack" runat="server" Text="Back" OnClick="lbPlaceIveBeenBack_Click" /> </div> <div id="rightbutton"> <asp:LinkButton ID="lbPlaceIveBeenBeginning" runat="server" Text="Beginning" OnClick="lbPlaceIveBeenBeginning_Click" /> </div> </div> <div id="content"> <ul class="pageitem"> <li> <asp:HiddenField ID="hdPlaceIveBeenPlaceId" runat="server" /> <asp:HiddenField ID="hdPlaceIveBeenLatitude" runat="server" /> <asp:HiddenField ID="hdPlaceIveBeenLongitude" runat="server" /> <asp:Label ID="lblPlaceIveBeenName" runat="server" /><br /> <asp:Label ID="lblPlaceIveBeenAddress" runat="server" /><br /> <asp:Label ID="lblPlaceIveBeenCity" runat="server" />, <asp:Label ID="lblPlaceIveBeenState" runat="server" /> <asp:Label ID="lblPlaceIveBeenZipCode" runat="server" /><br /> <asp:Label ID="lblPlaceIveBeenCountry" runat="server" /><br /> <div id="divPlaceIveBeen" style="width:300px; height:300px"></div> </li> </ul> </div> </asp:Panel> <asp:Panel ID="pnlAddPlace" runat="server" Visible="false"> <div id="topbar"><div id="title">MapSplore</div><div id="leftbutton"><asp:LinkButton ID="lbAddPlaceReturn" runat="server" Text="Back" OnClick="lbAddPlaceReturn_Click" /></div><div id="rightnav"></div></div><div id="content"> <ul class="pageitem"> <li id="liPlaceAddMessage" runat="server" visible="false"> <asp:Label ID="PlaceAddMessage" runat="server" /> </li> <li class="bigfield"> <asp:TextBox ID="txtPlaceName" runat="server" placeholder="Name of Establishment" /> </li> <li class="bigfield"> <asp:TextBox ID="txtAddress1" runat="server" placeholder="Address 1" /> </li> <li class="bigfield"> <asp:TextBox ID="txtCity" runat="server" placeholder="City" /> </li> <li class="select"> <asp:DropDownList ID="ddlProvince" runat="server" placeholder="Select State" /> <span class="arrow"></span> </li> <li class="bigfield"> <asp:TextBox ID="txtZipCode" runat="server" placeholder="Zip Code" /> </li> <li class="select"> <asp:DropDownList ID="ddlCountry" runat="server" onselectedindexchanged="ddlCountry_SelectedIndexChanged" /> <span class="arrow"></span> </li> <li class="bigfield"> <asp:TextBox ID="txtPhoneNumber" runat="server" placeholder="Phone Number" /> </li> <li class="checkbox"> <span class="name">You Here Now:</span> <asp:CheckBox ID="cbYouHereNow" runat="server" Checked="true" /> </li> <li class="button"> <asp:Button ID="btnAdd" runat="server" Text="Add Place" onclick="btnAdd_Click" /> </li> </ul></div> </asp:Panel> <asp:Panel ID="pnlImHere" runat="server" Visible="false"> <asp:TextBox ID="txtImHere" runat="server" TextMode="MultiLine" Rows="3" Columns="40" /><br /> <asp:DropDownList ID="ddlPlace" runat="server" /><br /> <asp:Button ID="btnHere" runat="server" Text="Tell Everyone I'm Here" onclick="btnHere_Click" /><br /> </asp:Panel> </div> </ContentTemplate> </asp:UpdatePanel> </asp:Content> Code Behind .cs file: using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.HtmlControls;using System.Web.UI.WebControls;using LocationDataModel; public partial class AT_iPhone_Default : ViewStatePage{ private iPhoneDevice ipd; protected void Page_Load(object sender, EventArgs e) { LocationDataEntities lde = new LocationDataEntities(); if (!Page.IsPostBack) { var Countries = from c in lde.Countries select c; foreach (Country co in Countries) { ddlCountry.Items.Add(new ListItem(co.Name, co.CountryId.ToString())); } ddlCountry_SelectedIndexChanged(ddlCountry, null); if (AppleIPhone.IsIPad()) ipd = iPhoneDevice.iPad; if (AppleIPhone.IsIPhone()) ipd = iPhoneDevice.iPhone; if (AppleIPhone.IsIPodTouch()) ipd = iPhoneDevice.iPodTouch; } } protected void btnPlaces_Click(object sender, EventArgs e) { } protected void btnAdd_Click(object sender, EventArgs e) { bool blImHere = cbYouHereNow.Checked; string Place = txtPlaceName.Text, Address1 = txtAddress1.Text, City = txtCity.Text, ZipCode = txtZipCode.Text, PhoneNumber = txtPhoneNumber.Text, ProvinceId = ddlProvince.SelectedItem.Value, CountryId = ddlCountry.SelectedItem.Value; int iProvinceId, iCountryId; double dLatitude, dLongitude; DataAccess da = new DataAccess(); if ((!String.IsNullOrEmpty(ProvinceId)) && (!String.IsNullOrEmpty(CountryId))) { iProvinceId = Convert.ToInt32(ProvinceId); iCountryId = Convert.ToInt32(CountryId); if (blImHere) { dLatitude = Convert.ToDouble(Latitude.Value); dLongitude = Convert.ToDouble(Longitude.Value); da.StorePlace(Place, Address1, String.Empty, City, iProvinceId, ZipCode, iCountryId, PhoneNumber, dLatitude, dLongitude); } else { da.StorePlace(Place, Address1, String.Empty, City, iProvinceId, ZipCode, iCountryId, PhoneNumber); } liPlaceAddMessage.Visible = true; PlaceAddMessage.Text = "Awesome, your place has been added. Add Another!"; txtPlaceName.Text = String.Empty; txtAddress1.Text = String.Empty; txtCity.Text = String.Empty; ddlProvince.SelectedIndex = -1; txtZipCode.Text = String.Empty; txtPhoneNumber.Text = String.Empty; } else { liPlaceAddMessage.Visible = true; PlaceAddMessage.Text = "Please select a State and a Country."; } } protected void ddlCountry_SelectedIndexChanged(object sender, EventArgs e) { string CountryId = ddlCountry.SelectedItem.Value; if (!String.IsNullOrEmpty(CountryId)) { int iCountryId = Convert.ToInt32(CountryId); LocationDataModel.LocationDataEntities lde = new LocationDataModel.LocationDataEntities(); var prov = from p in lde.Provinces where p.CountryId == iCountryId orderby p.ProvinceName select p; ddlProvince.Items.Add(String.Empty); foreach (Province pr in prov) { ddlProvince.Items.Add(new ListItem(pr.ProvinceName, pr.ProvinceId.ToString())); } } else { ddlProvince.Items.Clear(); } } protected void btnImHere_Click(object sender, EventArgs e) { int i = 0; DataAccess da = new DataAccess(); double Lat = Convert.ToDouble(Latitude.Value), Lon = Convert.ToDouble(Longitude.Value); List<Place> lp = da.NearByLocations(Lat, Lon); foreach (Place p in lp) { ListItem li = new ListItem(p.Name, p.PlaceId.ToString()); if (i == 0) { li.Selected = true; } ddlPlace.Items.Add(li); i++; } pnlAddPlace.Visible = false; pnlImHere.Visible = true; } protected void lbImHere_Click(object sender, EventArgs e) { string UserName = Membership.GetUser().UserName; ListViewItem lvi = (ListViewItem)(((LinkButton)sender).Parent); HiddenField hd = (HiddenField)lvi.FindControl("hdPlaceId"); long PlaceId = Convert.ToInt64(hd.Value); double dLatitude = Convert.ToDouble(Latitude.Value); double dLongitude = Convert.ToDouble(Longitude.Value); DataAccess da = new DataAccess(); Place pl = da.GetPlace(PlaceId); pnlImHereNow.Visible = true; pnlPlaces.Visible = false; hdPlaceId.Value = PlaceId.ToString(); hdPlaceLat.Value = pl.Latitude.ToString(); hdPlaceLon.Value = pl.Longitude.ToString(); hdPlaceTitle.Value = pl.Name; lblPlaceTitle.Text = pl.Name; } protected void btnHere_Click(object sender, EventArgs e) { string UserName = Membership.GetUser().UserName; string WhatsH = txtImHere.Text; long PlaceId = Convert.ToInt64(ddlPlace.SelectedValue); double dLatitude = Convert.ToDouble(Latitude.Value); double dLongitude = Convert.ToDouble(Longitude.Value); DataAccess da = new DataAccess(); da.StoreUserAT(UserName, PlaceId, WhatsH, dLatitude, dLongitude); } protected void btnLocalCoupons_Click(object sender, EventArgs e) { double dLatitude = Convert.ToDouble(Latitude.Value); double dLongitude = Convert.ToDouble(Longitude.Value); DataAccess da = new DataAccess(); } protected void lbBusiness_Click(object sender, EventArgs e) { string UserName = Membership.GetUser().UserName; GridViewRow gvr = (GridViewRow)(((LinkButton)sender).Parent.Parent); HiddenField hd = (HiddenField)gvr.FindControl("hdPlaceId"); string sPlaceId = hd.Value; Int64 PlaceId; if (!String.IsNullOrEmpty(sPlaceId)) { PlaceId = Convert.ToInt64(sPlaceId); } } protected void lbLocalDeals_Click(object sender, EventArgs e) { double dLatitude = Convert.ToDouble(Latitude.Value); double dLongitude = Convert.ToDouble(Longitude.Value); DataAccess da = new DataAccess(); pnlCoupons.Visible = true; pnlStart.Visible = false; List<GeoPromotion> lgp = da.NearByDeals(dLatitude, dLongitude); lvCoupons.DataSource = lgp; lvCoupons.DataBind(); } protected void lbLocalPlaces_Click(object sender, EventArgs e) { DataAccess da = new DataAccess(); double Lat = Convert.ToDouble(Latitude.Value); double Lon = Convert.ToDouble(Longitude.Value); List<LocationDataModel.Place> places = da.NearByLocations(Lat, Lon); lvPlaces.DataSource = places; lvPlaces.SelectedIndex = -1; lvPlaces.DataBind(); pnlPlaces.Visible = true; pnlStart.Visible = false; } protected void ReturnFromPlaces_Click(object sender, EventArgs e) { pnlPlaces.Visible = false; pnlStart.Visible = true; } protected void ReturnFromDeals_Click(object sender, EventArgs e) { pnlCoupons.Visible = false; pnlStart.Visible = true; } protected void btnImHereNow_Click(object sender, EventArgs e) { long PlaceId = Convert.ToInt32(hdPlaceId.Value); string UserName = Membership.GetUser().UserName; string WhatsHappening = txtWhatsHappening.Text; double UserLat = Convert.ToDouble(Latitude.Value); double UserLon = Convert.ToDouble(Longitude.Value); DataAccess da = new DataAccess(); da.StoreUserAT(UserName, PlaceId, WhatsHappening, UserLat, UserLon); } protected void lbImHereNowReturn_Click(object sender, EventArgs e) { pnlImHereNow.Visible = false; pnlPlaces.Visible = true; } protected void lbBackToBeginning_Click(object sender, EventArgs e) { pnlStart.Visible = true; pnlImHereNow.Visible = false; } protected void lbWhereIveBeen_Click(object sender, EventArgs e) { string UserName = Membership.GetUser().UserName; pnlStart.Visible = false; pnlIveBeenHere.Visible = true; DataAccess da = new DataAccess(); lvWhereIveBeen.DataSource = da.UserATs(UserName, 0, 15); lvWhereIveBeen.DataBind(); } protected void lbIveBeenHereBack_Click(object sender, EventArgs e) { pnlIveBeenHere.Visible = false; pnlStart.Visible = true; } protected void lbPlaceIveBeen_Click(object sender, EventArgs e) { LinkButton lb = (LinkButton)sender; ListViewItem lvi = (ListViewItem)lb.Parent.Parent; HiddenField hdATID = (HiddenField)lvi.FindControl("hdATID"); Int64 ATID = Convert.ToInt64(hdATID.Value); DataAccess da = new DataAccess(); pnlIveBeenHere.Visible = false; pnlPlaceIveBeen.Visible = true; var plac = da.GetPlaceViaATID(ATID); hdPlaceIveBeenPlaceId.Value = plac.PlaceId.ToString(); hdPlaceIveBeenLatitude.Value = plac.Latitude.ToString(); hdPlaceIveBeenLongitude.Value = plac.Longitude.ToString(); lblPlaceIveBeenName.Text = plac.Name; lblPlaceIveBeenAddress.Text = plac.Address1; lblPlaceIveBeenCity.Text = plac.City; lblPlaceIveBeenState.Text = plac.Province.ProvinceName; lblPlaceIveBeenZipCode.Text = plac.ZipCode; lblPlaceIveBeenCountry.Text = plac.Country.Name; } protected void lbNotListed_Click(object sender, EventArgs e) { SetupAddPoint(); pnlPlaces.Visible = false; } protected void lbAddAPlace_Click(object sender, EventArgs e) { SetupAddPoint(); } private void SetupAddPoint() { double lat = Convert.ToDouble(Latitude.Value); double lon = Convert.ToDouble(Longitude.Value); DataAccess da = new DataAccess(); var zip = da.WhereAmIAt(lat, lon); if (zip.Count > 0) { var z0 = zip[0]; txtCity.Text = z0.City; txtZipCode.Text = z0.ZipCode; ddlProvince.ClearSelection(); if (z0.ProvinceId.HasValue == true) { foreach (ListItem li in ddlProvince.Items) { if (li.Value == z0.ProvinceId.Value.ToString()) { li.Selected = true; break; } } } } pnlAddPlace.Visible = true; pnlStart.Visible = false; } protected void lbAddPlaceReturn_Click(object sender, EventArgs e) { pnlAddPlace.Visible = false; pnlStart.Visible = true; liPlaceAddMessage.Visible = false; PlaceAddMessage.Text = String.Empty; } protected void lbPlaceIveBeenBack_Click(object sender, EventArgs e) { pnlIveBeenHere.Visible = true; pnlPlaceIveBeen.Visible = false; } protected void lbPlaceIveBeenBeginning_Click(object sender, EventArgs e) { pnlPlaceIveBeen.Visible = false; pnlStart.Visible = true; } protected string DisplayName(object val) { string strVal = Convert.ToString(val); if (AppleIPhone.IsIPad()) { ipd = iPhoneDevice.iPad; } if (AppleIPhone.IsIPhone()) { ipd = iPhoneDevice.iPhone; } if (AppleIPhone.IsIPodTouch()) { ipd = iPhoneDevice.iPodTouch; } return (iPhoneHelper.DisplayContentOnMenu(strVal, ipd)); }} iPhoneHelper.cs file: using System;using System.Collections.Generic;using System.Linq;using System.Web; public enum iPhoneDevice{ iPhone, iPodTouch, iPad}/// <summary>/// Summary description for iPhoneHelper/// </summary>/// public class iPhoneHelper{ public iPhoneHelper() { // // TODO: Add constructor logic here // } // This code is stupid in retrospect. Use css to solve this problem public static string DisplayContentOnMenu(string val, iPhoneDevice ipd) { string Return = val; string Elipsis = "..."; int iPadMaxLength = 30; int iPhoneMaxLength = 15; if (ipd == iPhoneDevice.iPad) { if (Return.Length > iPadMaxLength) { Return = Return.Substring(0, iPadMaxLength - Elipsis.Length) + Elipsis; } } else { if (Return.Length > iPhoneMaxLength) { Return = Return.Substring(0, iPhoneMaxLength - Elipsis.Length) + Elipsis; } } return (Return); }} Source code for the ViewStatePage: using System;using System.Data;using System.Data.SqlClient;using System.Configuration;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.WebControls;using System.Web.UI.WebControls.WebParts;using System.Web.UI.HtmlControls; /// <summary>/// Summary description for BasePage/// </summary>#region Base class for a page.public class ViewStatePage : System.Web.UI.Page{ PageStatePersisterToDatabase myPageStatePersister; public ViewStatePage() : base() { myPageStatePersister = new PageStatePersisterToDatabase(this); } protected override PageStatePersister PageStatePersister { get { return myPageStatePersister; } } }#endregion #region This class will override the page persistence to store page state in a database.public class PageStatePersisterToDatabase : PageStatePersister{ private string ViewStateKeyField = "__VIEWSTATE_KEY"; private string _exNoConnectionStringFound = "No Database Configuration information is in the web.config."; public PageStatePersisterToDatabase(Page page) : base(page) { } public override void Load() { // Get the cache key from the web form data System.Int64 key = Convert.ToInt64(Page.Request.Params[ViewStateKeyField]); Pair state = this.LoadState(key); // Abort if cache object is not of type Pair if (state == null) throw new ApplicationException("Missing valid " + ViewStateKeyField); // Set view state and control state ViewState = state.First; ControlState = state.Second; } public override void Save() { // No processing needed if no states available if (ViewState == null && ControlState != null) return; System.Int64 key; IStateFormatter formatter = this.StateFormatter; Pair statePair = new Pair(ViewState, ControlState); // Serialize the statePair object to a string. string serializedState = formatter.Serialize(statePair); // Save the ViewState and get a unique identifier back. key = SaveState(serializedState); // Register hidden field to store cache key in // Page.ClientScript does not work properly with Atlas. //Page.ClientScript.RegisterHiddenField(ViewStateKeyField, key.ToString()); ScriptManager.RegisterHiddenField(this.Page, ViewStateKeyField, key.ToString()); } private System.Int64 SaveState(string PageState) { System.Int64 i64Key = 0; string strConn = String.Empty, strProvider = String.Empty; string strSql = "insert into tblPageState ( SerializedState ) values ( '" + SqlEscape(PageState) + "');select scope_identity();"; SqlConnection sqlCn; SqlCommand sqlCm; try { GetDBConnectionString(ref strConn, ref strProvider); sqlCn = new SqlConnection(strConn); sqlCm = new SqlCommand(strSql, sqlCn); sqlCn.Open(); i64Key = Convert.ToInt64(sqlCm.ExecuteScalar()); if (sqlCn.State != ConnectionState.Closed) { sqlCn.Close(); } sqlCn.Dispose(); sqlCm.Dispose(); } finally { sqlCn = null; sqlCm = null; } return i64Key; } private Pair LoadState(System.Int64 iKey) { string strConn = String.Empty, strProvider = String.Empty, SerializedState = String.Empty, strMinutesInPast = GetMinutesInPastToDelete(); Pair PageState; string strSql = "select SerializedState from tblPageState where tblPageStateID=" + iKey.ToString() + ";" + "delete from tblPageState where DateUpdated<DateAdd(mi, " + strMinutesInPast + ", getdate());"; SqlConnection sqlCn; SqlCommand sqlCm; try { GetDBConnectionString(ref strConn, ref strProvider); sqlCn = new SqlConnection(strConn); sqlCm = new SqlCommand(strSql, sqlCn); sqlCn.Open(); SerializedState = Convert.ToString(sqlCm.ExecuteScalar()); IStateFormatter formatter = this.StateFormatter; if ((null == SerializedState) || (String.Empty == SerializedState)) { throw (new ApplicationException("No ViewState records were returned.")); } // Deserilize returns the Pair object that is serialized in // the Save method. PageState = (Pair)formatter.Deserialize(SerializedState); if (sqlCn.State != ConnectionState.Closed) { sqlCn.Close(); } sqlCn.Dispose(); sqlCm.Dispose(); } finally { sqlCn = null; sqlCm = null; } return PageState; } private string SqlEscape(string Val) { string ReturnVal = String.Empty; if (null != Val) { ReturnVal = Val.Replace("'", "''"); } return (ReturnVal); } private void GetDBConnectionString(ref string ConnectionStringValue, ref string ProviderNameValue) { if (System.Configuration.ConfigurationManager.ConnectionStrings.Count > 0) { ConnectionStringValue = System.Configuration.ConfigurationManager.ConnectionStrings["ApplicationServices"].ConnectionString; ProviderNameValue = System.Configuration.ConfigurationManager.ConnectionStrings["ApplicationServices"].ProviderName; } else { throw new ConfigurationErrorsException(_exNoConnectionStringFound); } } private string GetMinutesInPastToDelete() { string strReturn = "-60"; if (null != System.Configuration.ConfigurationManager.AppSettings["MinutesInPastToDeletePageState"]) { strReturn = System.Configuration.ConfigurationManager.AppSettings["MinutesInPastToDeletePageState"].ToString(); } return (strReturn); }}#endregion AppleiPhone.cs file: using System;using System.Collections.Generic;using System.Linq;using System.Web; /// <summary>/// Summary description for AppleIPhone/// </summary>public class AppleIPhone{ public AppleIPhone() { // // TODO: Add constructor logic here // } static public bool IsIPhoneOS() { return (IsIPad() || IsIPhone() || IsIPodTouch()); } static public bool IsIPhone() { return IsTest("iPhone"); } static public bool IsIPodTouch() { return IsTest("iPod"); } static public bool IsIPad() { return IsTest("iPad"); } static private bool IsTest(string Agent) { bool bl = false; string ua = HttpContext.Current.Request.UserAgent.ToLower(); try { bl = ua.Contains(Agent.ToLower()); } catch { } return (bl); }} Master page .cs: using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.HtmlControls;using System.Web.UI.WebControls; public partial class MasterPages_iPhoneMaster : System.Web.UI.MasterPage{ protected void Page_Load(object sender, EventArgs e) { HtmlHead head = Page.Header; HtmlMeta meta = new HtmlMeta(); if (AppleIPhone.IsIPad() == true) { meta.Content = "width=400,user-scalable=no"; head.Controls.Add(meta); } else { meta.Content = "width=device-width, user-scalable=no"; meta.Attributes.Add("name", "viewport"); } meta.Attributes.Add("name", "viewport"); head.Controls.Add(meta); HtmlLink cssLink = new HtmlLink(); HtmlGenericControl script = new HtmlGenericControl("script"); script.Attributes.Add("type", "text/javascript"); script.Attributes.Add("src", ResolveUrl("~/Scripts/iWebKit/javascript/functions.js")); head.Controls.Add(script); cssLink.Attributes.Add("rel", "stylesheet"); cssLink.Attributes.Add("href", ResolveUrl("~/Scripts/iWebKit/css/style.css") ); cssLink.Attributes.Add("type", "text/css"); head.Controls.Add(cssLink); HtmlGenericControl jsLink = new HtmlGenericControl("script"); //jsLink.Attributes.Add("type", "text/javascript"); //jsLink.Attributes.Add("src", ResolveUrl("~/Scripts/jquery-1.4.1.min.js") ); //head.Controls.Add(jsLink); HtmlLink appleIcon = new HtmlLink(); appleIcon.Attributes.Add("rel", "apple-touch-icon"); appleIcon.Attributes.Add("href", ResolveUrl("~/apple-touch-icon.png")); HtmlMeta appleMobileWebAppStatusBarStyle = new HtmlMeta(); appleMobileWebAppStatusBarStyle.Attributes.Add("name", "apple-mobile-web-app-status-bar-style"); appleMobileWebAppStatusBarStyle.Attributes.Add("content", "black"); head.Controls.Add(appleMobileWebAppStatusBarStyle); } internal string FindPath(string Location) { string Url = Server.MapPath(Location); return (Url); }}

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Parallelism in .NET – Part 6, Declarative Data Parallelism

- by Reed

When working with a problem that can be decomposed by data, we have a collection, and some operation being performed upon the collection. I’ve demonstrated how this can be parallelized using the Task Parallel Library and imperative programming using imperative data parallelism via the Parallel class. While this provides a huge step forward in terms of power and capabilities, in many cases, special care must still be given for relative common scenarios. C# 3.0 and Visual Basic 9.0 introduced a new, declarative programming model to .NET via the LINQ Project. When working with collections, we can now write software that describes what we want to occur without having to explicitly state how the program should accomplish the task. By taking advantage of LINQ, many operations become much shorter, more elegant, and easier to understand and maintain. Version 4.0 of the .NET framework extends this concept into the parallel computation space by introducing Parallel LINQ. Before we delve into PLINQ, let’s begin with a short discussion of LINQ. LINQ, the extensions to the .NET Framework which implement language integrated query, set, and transform operations, is implemented in many flavors. For our purposes, we are interested in LINQ to Objects. When dealing with parallelizing a routine, we typically are dealing with in-memory data storage. More data-access oriented LINQ variants, such as LINQ to SQL and LINQ to Entities in the Entity Framework fall outside of our concern, since the parallelism there is the concern of the data base engine processing the query itself. LINQ (LINQ to Objects in particular) works by implementing a series of extension methods, most of which work on IEnumerable<T>. The language enhancements use these extension methods to create a very concise, readable alternative to using traditional foreach statement. For example, let’s revisit our minimum aggregation routine we wrote in Part 4: double min = double.MaxValue; foreach(var item in collection) { double value = item.PerformComputation(); min = System.Math.Min(min, value); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Here, we’re doing a very simple computation, but writing this in an imperative style. This can be loosely translated to English as: Create a very large number, and save it in min Loop through each item in the collection. For every item: Perform some computation, and save the result If the computation is less than min, set min to the computation Although this is fairly easy to follow, it’s quite a few lines of code, and it requires us to read through the code, step by step, line by line, in order to understand the intention of the developer. We can rework this same statement, using LINQ: double min = collection.Min(item => item.PerformComputation()); Here, we’re after the same information. However, this is written using a declarative programming style. When we see this code, we’d naturally translate this to English as: Save the Min value of collection, determined via calling item.PerformComputation() That’s it – instead of multiple logical steps, we have one single, declarative request. This makes the developer’s intentions very clear, and very easy to follow. The system is free to implement this using whatever method required. Parallel LINQ (PLINQ) extends LINQ to Objects to support parallel operations. This is a perfect fit in many cases when you have a problem that can be decomposed by data. To show this, let’s again refer to our minimum aggregation routine from Part 4, but this time, let’s review our final, parallelized version: // Safe, and fast! double min = double.MaxValue; // Make a "lock" object object syncObject = new object(); Parallel.ForEach( collection, // First, we provide a local state initialization delegate. () => double.MaxValue, // Next, we supply the body, which takes the original item, loop state, // and local state, and returns a new local state (item, loopState, localState) => { double value = item.PerformComputation(); return System.Math.Min(localState, value); }, // Finally, we provide an Action<TLocal>, to "merge" results together localState => { // This requires locking, but it's only once per used thread lock(syncObj) min = System.Math.Min(min, localState); } ); Here, we’re doing the same computation as above, but fully parallelized. Describing this in English becomes quite a feat: Create a very large number, and save it in min Create a temporary object we can use for locking Call Parallel.ForEach, specifying three delegates For the first delegate: Initialize a local variable to hold the local state to a very large number For the second delegate: For each item in the collection, perform some computation, save the result If the result is less than our local state, save the result in local state For the final delegate: Take a lock on our temporary object to protect our min variable Save the min of our min and local state variables Although this solves our problem, and does it in a very efficient way, we’ve created a set of code that is quite a bit more difficult to understand and maintain. PLINQ provides us with a very nice alternative. In order to use PLINQ, we need to learn one new extension method that works on IEnumerable<T> – ParallelEnumerable.AsParallel(). That’s all we need to learn in order to use PLINQ: one single method. We can write our minimum aggregation in PLINQ very simply: double min = collection.AsParallel().Min(item => item.PerformComputation()); By simply adding “.AsParallel()” to our LINQ to Objects query, we converted this to using PLINQ and running this computation in parallel! This can be loosely translated into English easily, as well: Process the collection in parallel Get the Minimum value, determined by calling PerformComputation on each item Here, our intention is very clear and easy to understand. We just want to perform the same operation we did in serial, but run it “as parallel”. PLINQ completely extends LINQ to Objects: the entire functionality of LINQ to Objects is available. By simply adding a call to AsParallel(), we can specify that a collection should be processed in parallel. This is simple, safe, and incredibly useful.

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Why does async BeginReceiveFrom never time out on a raw socket?

- by James Hugard

Writing an asynchronous Ping using Raw Sockets in F#, to enable parallel requests using as few threads as possible. Not using "System.Net.NetworkInformation.Ping", because it appears to allocate one thread per request. Am also interested in using F# async workflows. The synchronous version below correctly times out when the target host does not exist/respond, but the asynchronous version hangs. Both work when the host does respond. Not sure if this is a .NET issue, or an F# one... Any ideas? (note: the process must run as Admin to allow Raw Socket access) This throws a timeout: let result = Ping.Ping ( IPAddress.Parse( "192.168.33.22" ), 1000 ) However, this hangs: let result = Ping.AsyncPing ( IPAddress.Parse( "192.168.33.22" ), 1000 ) |> Async.RunSynchronously Here's the code... module Ping open System open System.Net open System.Net.Sockets open System.Threading //---- ICMP Packet Classes type IcmpMessage (t : byte) = let mutable m_type = t let mutable m_code = 0uy let mutable m_checksum = 0us member this.Type with get() = m_type member this.Code with get() = m_code member this.Checksum = m_checksum abstract Bytes : byte array default this.Bytes with get() = [| m_type m_code byte(m_checksum) byte(m_checksum >>> 8) |] member this.GetChecksum() = let mutable sum = 0ul let bytes = this.Bytes let mutable i = 0 // Sum up uint16s while i < bytes.Length - 1 do sum <- sum + uint32(BitConverter.ToUInt16( bytes, i )) i <- i + 2 // Add in last byte, if an odd size buffer if i <> bytes.Length then sum <- sum + uint32(bytes.[i]) // Shuffle the bits sum <- (sum >>> 16) + (sum &&& 0xFFFFul) sum <- sum + (sum >>> 16) sum <- ~~~sum uint16(sum) member this.UpdateChecksum() = m_checksum <- this.GetChecksum() type InformationMessage (t : byte) = inherit IcmpMessage(t) let mutable m_identifier = 0us let mutable m_sequenceNumber = 0us member this.Identifier = m_identifier member this.SequenceNumber = m_sequenceNumber override this.Bytes with get() = Array.append (base.Bytes) [| byte(m_identifier) byte(m_identifier >>> 8) byte(m_sequenceNumber) byte(m_sequenceNumber >>> 8) |] type EchoMessage() = inherit InformationMessage( 8uy ) let mutable m_data = Array.create 32 32uy do base.UpdateChecksum() member this.Data with get() = m_data and set(d) = m_data <- d this.UpdateChecksum() override this.Bytes with get() = Array.append (base.Bytes) (this.Data) //---- Synchronous Ping let Ping (host : IPAddress, timeout : int ) = let mutable ep = new IPEndPoint( host, 0 ) let socket = new Socket( AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.SendTimeout, timeout ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, timeout ) let packet = EchoMessage() let mutable buffer = packet.Bytes try if socket.SendTo( buffer, ep ) <= 0 then raise (SocketException()) buffer <- Array.create (buffer.Length + 20) 0uy let mutable epr = ep :> EndPoint if socket.ReceiveFrom( buffer, &epr ) <= 0 then raise (SocketException()) finally socket.Close() buffer //---- Entensions to the F# Async class to allow up to 5 paramters (not just 3) type Async with static member FromBeginEnd(arg1,arg2,arg3,arg4,beginAction,endAction,?cancelAction): Async<'T> = Async.FromBeginEnd((fun (iar,state) -> beginAction(arg1,arg2,arg3,arg4,iar,state)), endAction, ?cancelAction=cancelAction) static member FromBeginEnd(arg1,arg2,arg3,arg4,arg5,beginAction,endAction,?cancelAction): Async<'T> = Async.FromBeginEnd((fun (iar,state) -> beginAction(arg1,arg2,arg3,arg4,arg5,iar,state)), endAction, ?cancelAction=cancelAction) //---- Extensions to the Socket class to provide async SendTo and ReceiveFrom type System.Net.Sockets.Socket with member this.AsyncSendTo( buffer, offset, size, socketFlags, remoteEP ) = Async.FromBeginEnd( buffer, offset, size, socketFlags, remoteEP, this.BeginSendTo, this.EndSendTo ) member this.AsyncReceiveFrom( buffer, offset, size, socketFlags, remoteEP ) = Async.FromBeginEnd( buffer, offset, size, socketFlags, remoteEP, this.BeginReceiveFrom, (fun asyncResult -> this.EndReceiveFrom(asyncResult, remoteEP) ) ) //---- Asynchronous Ping let AsyncPing (host : IPAddress, timeout : int ) = async { let ep = IPEndPoint( host, 0 ) use socket = new Socket( AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.SendTimeout, timeout ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, timeout ) let packet = EchoMessage() let outbuffer = packet.Bytes try let! result = socket.AsyncSendTo( outbuffer, 0, outbuffer.Length, SocketFlags.None, ep ) if result <= 0 then raise (SocketException()) let epr = ref (ep :> EndPoint) let inbuffer = Array.create (outbuffer.Length + 256) 0uy let! result = socket.AsyncReceiveFrom( inbuffer, 0, inbuffer.Length, SocketFlags.None, epr ) if result <= 0 then raise (SocketException()) return inbuffer finally socket.Close() }

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How to detect a timeout when using asynchronous Socket.BeginReceive?

- by James Hugard

Writing an asynchronous Ping using Raw Sockets in F#, to enable parallel requests using as few threads as possible. Not using "System.Net.NetworkInformation.Ping", because it appears to allocate one thread per request. Am also interested in using F# async workflows. The synchronous version below correctly times out when the target host does not exist/respond, but the asynchronous version hangs. Both work when the host does respond. Not sure if this is a .NET issue, or an F# one... Any ideas? (note: the process must run as Admin to allow Raw Socket access) This throws a timeout: let result = Ping.Ping ( IPAddress.Parse( "192.168.33.22" ), 1000 ) However, this hangs: let result = Ping.AsyncPing ( IPAddress.Parse( "192.168.33.22" ), 1000 ) |> Async.RunSynchronously Here's the code... module Ping open System open System.Net open System.Net.Sockets open System.Threading //---- ICMP Packet Classes type IcmpMessage (t : byte) = let mutable m_type = t let mutable m_code = 0uy let mutable m_checksum = 0us member this.Type with get() = m_type member this.Code with get() = m_code member this.Checksum = m_checksum abstract Bytes : byte array default this.Bytes with get() = [| m_type m_code byte(m_checksum) byte(m_checksum >>> 8) |] member this.GetChecksum() = let mutable sum = 0ul let bytes = this.Bytes let mutable i = 0 // Sum up uint16s while i < bytes.Length - 1 do sum <- sum + uint32(BitConverter.ToUInt16( bytes, i )) i <- i + 2 // Add in last byte, if an odd size buffer if i <> bytes.Length then sum <- sum + uint32(bytes.[i]) // Shuffle the bits sum <- (sum >>> 16) + (sum &&& 0xFFFFul) sum <- sum + (sum >>> 16) sum <- ~~~sum uint16(sum) member this.UpdateChecksum() = m_checksum <- this.GetChecksum() type InformationMessage (t : byte) = inherit IcmpMessage(t) let mutable m_identifier = 0us let mutable m_sequenceNumber = 0us member this.Identifier = m_identifier member this.SequenceNumber = m_sequenceNumber override this.Bytes with get() = Array.append (base.Bytes) [| byte(m_identifier) byte(m_identifier >>> 8) byte(m_sequenceNumber) byte(m_sequenceNumber >>> 8) |] type EchoMessage() = inherit InformationMessage( 8uy ) let mutable m_data = Array.create 32 32uy do base.UpdateChecksum() member this.Data with get() = m_data and set(d) = m_data <- d this.UpdateChecksum() override this.Bytes with get() = Array.append (base.Bytes) (this.Data) //---- Synchronous Ping let Ping (host : IPAddress, timeout : int ) = let mutable ep = new IPEndPoint( host, 0 ) let socket = new Socket( AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.SendTimeout, timeout ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, timeout ) let packet = EchoMessage() let mutable buffer = packet.Bytes try if socket.SendTo( buffer, ep ) <= 0 then raise (SocketException()) buffer <- Array.create (buffer.Length + 20) 0uy let mutable epr = ep :> EndPoint if socket.ReceiveFrom( buffer, &epr ) <= 0 then raise (SocketException()) finally socket.Close() buffer //---- Entensions to the F# Async class to allow up to 5 paramters (not just 3) type Async with static member FromBeginEnd(arg1,arg2,arg3,arg4,beginAction,endAction,?cancelAction): Async<'T> = Async.FromBeginEnd((fun (iar,state) -> beginAction(arg1,arg2,arg3,arg4,iar,state)), endAction, ?cancelAction=cancelAction) static member FromBeginEnd(arg1,arg2,arg3,arg4,arg5,beginAction,endAction,?cancelAction): Async<'T> = Async.FromBeginEnd((fun (iar,state) -> beginAction(arg1,arg2,arg3,arg4,arg5,iar,state)), endAction, ?cancelAction=cancelAction) //---- Extensions to the Socket class to provide async SendTo and ReceiveFrom type System.Net.Sockets.Socket with member this.AsyncSendTo( buffer, offset, size, socketFlags, remoteEP ) = Async.FromBeginEnd( buffer, offset, size, socketFlags, remoteEP, this.BeginSendTo, this.EndSendTo ) member this.AsyncReceiveFrom( buffer, offset, size, socketFlags, remoteEP ) = Async.FromBeginEnd( buffer, offset, size, socketFlags, remoteEP, this.BeginReceiveFrom, (fun asyncResult -> this.EndReceiveFrom(asyncResult, remoteEP) ) ) //---- Asynchronous Ping let AsyncPing (host : IPAddress, timeout : int ) = async { let ep = IPEndPoint( host, 0 ) use socket = new Socket( AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.SendTimeout, timeout ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, timeout ) let packet = EchoMessage() let outbuffer = packet.Bytes try let! result = socket.AsyncSendTo( outbuffer, 0, outbuffer.Length, SocketFlags.None, ep ) if result <= 0 then raise (SocketException()) let epr = ref (ep :> EndPoint) let inbuffer = Array.create (outbuffer.Length + 256) 0uy let! result = socket.AsyncReceiveFrom( inbuffer, 0, inbuffer.Length, SocketFlags.None, epr ) if result <= 0 then raise (SocketException()) return inbuffer finally socket.Close() }

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How do I disable the touchpad using the upper left corner on an HP Pavilion dv6?

- by William

To disable the touchpad on an HP Pavilion dv6, you double tap on an area in the upper left hand corner of the touchpad. Then the blue indicator light around the border of the touchpad turns red, and the touchpad is disabled. Double tapping on this area again turns the touchpad turns back on. I do a lot of typing, and frequently bump the touchpad, messing up my work and annoying me. So, I would like to enable the ability to disable the touchpad by double-tapping on the area in the upper left hand corner. Unfortunately, there is no function key backup to disable the touchpad. This does not work in Ubuntu. I can turn it off using touchpad-indicator, but the program must be manually started and you have to disable using the key combination. Double-tapping the area is much easier. My computer is the HP Pavilion dv6-6135dx. Any help would be greatly appreciated.

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Convert NSData to primitive variable with ieee-754 or twos-complement ?

- by William GILLARD

Hi every one. I am new programmer in Obj-C and cocoa. Im a trying to write a framework which will be used to read a binary files (Flexible Image Transport System or FITS binary files, usually used by astronomers). The binary data, that I am interested to extract, can have various formats and I get its properties by reading the header of the FITS file. Up to now, I manage to create a class to store the content of the FITS file and to isolate the header into a NSString object and the binary data into a NSData object. I also manage to write method which allow me to extract the key values from the header that are very valuable to interpret the binary data. I am now trying to convert the NSData object into a primitive array (array of double, int, short ...). But, here, I get stuck and would appreciate any help. According to the documentation I have about the FITS file, I have 5 possibilities to interpret the binary data depending on the value of the BITPIX key: BITPIX value | Data represented 8 | Char or unsigned binary int 16 | 16-bit two's complement binary integer 32 | 32-bit two's complement binary integer 64 | 64-bit two's complement binary integer -32 | IEEE single precision floating-point -64 | IEEE double precision floating-point I already write the peace of code, shown bellow, to try to convert the NSData into a primitive array. // self reefer to my FITS class which contain a NSString object // with the content of the header and a NSData object with the binary data. -(void*) GetArray { switch (BITPIX) { case 8: return [self GetArrayOfUInt]; break; case 16: return [self GetArrayOfInt]; break; case 32: return [self GetArrayOfLongInt]; break; case 64: return [self GetArrayOfLongLong]; break; case -32: return [self GetArrayOfFloat]; break; case -64: return [self GetArrayOfDouble]; break; default: return NULL; } } // then I show you the method to convert the NSData into a primitive array. // I restrict my example to the case of 'double'. Code is similar for other methods // just change double by 'unsigned int' (BITPIX 8), 'short' (BITPIX 16) // 'int' (BITPIX 32) 'long lon' (BITPIX 64), 'float' (BITPIX -32). -(double*) GetArrayOfDouble { int Nelements=[self NPIXEL]; // Metod to extract, from the header // the number of element into the array NSLog(@"TOTAL NUMBER OF ELEMENTS [%i]\n",Nelements); //CREATE THE ARRAY double (*array)[Nelements]; // Get the total number of bits in the binary data int Nbit = abs(BITPIX)*GCOUNT*(PCOUNT + Nelements); // GCOUNT and PCOUNT are defined // into the header NSLog(@"TOTAL NUMBER OF BIT [%i]\n",Nbit); int i=0; //FILL THE ARRAY double Value; for(int bit=0; bit < Nbit; bit+=sizeof(double)) { [Img getBytes:&Value range:NSMakeRange(bit,sizeof(double))]; NSLog(@"[%i]:(%u)%.8G\n",i,bit,Value); (*array)[i]=Value; i++; } return (*array); } However, the value I print in the loop are very different from the expected values (compared using official FITS software). Therefore, I think that the Obj-C double does not use the IEEE-754 convention as well as the Obj-C int are not twos-complement. I am really not familiar with this two convention (IEEE and twos-complement) and would like to know how I can do this conversion with Obj-C. In advance many thanks for any help or information.

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How do I obtain a code point integer from a 1 to 4 byte UTF-8 encoded sequence in Windows?

- by Patrick Niedzielski

Hello, I am Patrick Niedzielski, a programmer for the Free Software 3D adventure game Humm and Strumm. I'm working on a minimal Unicode character class in C++. I currently have an array of four bytes representing a UTF-8 sequence. On GNU/Linux, I can just convert to UTF-32 with iconv(), but on Windows, I cannot do this. Is it possible to convert the array to a single code point? Thanks, Patrick

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WSDL-world vs CLR-world – some differences

- by nmarun

A change in mindset is required when switching between a typical CLR application and a web service application. There are some things in a CLR environment that just don’t add-up in a WSDL arena (and vice-versa). I’m listing some of them here. When I say WSDL-world, I’m mostly talking with respect to a WCF Service and / or a Web Service. No (direct) Method Overloading: You definitely can have overloaded methods in a, say, Console application, but when it comes to a WCF / Web Services application, you need to adorn these overloaded methods with a special attribute so the service knows which specific method to invoke. When you’re working with WCF, use the Name property of the OperationContract attribute to provide unique names. 1: [OperationContract(Name = "AddInt")] 2: int Add(int arg1, int arg2); 3: 4: [OperationContract(Name = "AddDouble")] 5: double Add(double arg1, double arg2); By default, the proxy generates the code for this as: 1: [System.ServiceModel.OperationContractAttribute( 2: Action="http://tempuri.org/ILearnWcfService/AddInt", 3: ReplyAction="http://tempuri.org/ILearnWcfService/AddIntResponse")] 4: int AddInt(int arg1, int arg2); 5: 6: [System.ServiceModel.OperationContractAttribute( 7: Action="http://tempuri.org/ILearnWcfServiceExtend/AddDouble", 8: ReplyAction="http://tempuri.org/ILearnWcfServiceExtend/AddDoubleResponse")] 9: double AddDouble(double arg1, double arg2); With Web Services though the story is slightly different. Even after setting the MessageName property of the WebMethod attribute, the proxy does not change the name of the method, but only the underlying soap message changes. 1: [WebMethod] 2: public string HelloGalaxy() 3: { 4: return "Hello Milky Way!"; 5: } 6: 7: [WebMethod(MessageName = "HelloAnyGalaxy")] 8: public string HelloGalaxy(string galaxyName) 9: { 10: return string.Format("Hello {0}!", galaxyName); 11: } The one thing you need to remember is to set the WebServiceBinding accordingly. 1: [WebServiceBinding(ConformsTo = WsiProfiles.None)] The proxy is: 1: [System.Web.Services.Protocols.SoapDocumentMethodAttribute("http://tempuri.org/HelloGalaxy", 2: RequestNamespace="http://tempuri.org/", 3: ResponseNamespace="http://tempuri.org/", 4: Use=System.Web.Services.Description.SoapBindingUse.Literal, 5: ParameterStyle=System.Web.Services.Protocols.SoapParameterStyle.Wrapped)] 6: public string HelloGalaxy() 7: 8: [System.Web.Services.WebMethodAttribute(MessageName="HelloGalaxy1")] 9: [System.Web.Services.Protocols.SoapDocumentMethodAttribute("http://tempuri.org/HelloAnyGalaxy", 10: RequestElementName="HelloAnyGalaxy", 11: RequestNamespace="http://tempuri.org/", 12: ResponseElementName="HelloAnyGalaxyResponse", 13: ResponseNamespace="http://tempuri.org/", 14: Use=System.Web.Services.Description.SoapBindingUse.Literal, 15: ParameterStyle=System.Web.Services.Protocols.SoapParameterStyle.Wrapped)] 16: [return: System.Xml.Serialization.XmlElementAttribute("HelloAnyGalaxyResult")] 17: public string HelloGalaxy(string galaxyName) 18: You see the calling method name is the same in the proxy, however the soap message that gets generated is different. Using interchangeable data types: See details on this here. Type visibility: In a CLR-based application, if you mark a field as private, well we all know, it’s ‘private’. Coming to a WSDL side of things, in a Web Service, private fields and web methods will not get generated in the proxy. In WCF however, all your operation contracts will be public as they get implemented from an interface. Even in case your ServiceContract interface is declared internal/private, you will see it as a public interface in the proxy. This is because type visibility is a CLR concept and has no bearing on WCF. Also if a private field has the [DataMember] attribute in a data contract, it will get emitted in the proxy class as a public property for the very same reason. 1: [DataContract] 2: public struct Person 3: { 4: [DataMember] 5: private int _x; 6: 7: [DataMember] 8: public int Id { get; set; } 9: 10: [DataMember] 11: public string FirstName { get; set; } 12: 13: [DataMember] 14: public string Header { get; set; } 15: } 16: } See the ‘_x’ field is a private member with the [DataMember] attribute, but the proxy class shows as below: 1: [System.Runtime.Serialization.DataMemberAttribute()] 2: public int _x { 3: get { 4: return this._xField; 5: } 6: set { 7: if ((this._xField.Equals(value) != true)) { 8: this._xField = value; 9: this.RaisePropertyChanged("_x"); 10: } 11: } 12: } Passing derived types to web methods / operation contracts: Once again, in a CLR application, I can have a derived class be passed as a parameter where a base class is expected. I have the following set up for my WCF service. 1: [DataContract] 2: public class Employee 3: { 4: [DataMember(Name = "Id")] 5: public int EmployeeId { get; set; } 6: 7: [DataMember(Name="FirstName")] 8: public string FName { get; set; } 9: 10: [DataMember] 11: public string Header { get; set; } 12: } 13: 14: [DataContract] 15: public class Manager : Employee 16: { 17: [DataMember] 18: private int _x; 19: } 20: 21: // service contract 22: [OperationContract] 23: Manager SaveManager(Employee employee); 24: 25: // in my calling code 26: Manager manager = new Manager {_x = 1, FirstName = "abc"}; 27: manager = LearnWcfServiceClient.SaveManager(manager); The above will throw an exception saying: In short, this is saying, that a Manager type was found where an Employee type was expected! Hierarchy flattening of interfaces in WCF: See details on this here. In CLR world, you’ll see the entire hierarchy as is. That’s another difference. Using ref parameters: * can use ref for parameters, but operation contract should not be one-way (gives an error when you do an update service reference) => bad programming; create a return object that is composed of everything you need! This one kind of stumped me. Not sure why I tried this, but you can pass parameters prefixed with ref keyword* (* terms and conditions apply). The main issue is this, how would we know the changes that were made to a ‘ref’ input parameter are returned back from the service and updated to the local variable? Turns out both Web Services and WCF make this tracking happen by passing the input parameter in the response soap. This way when the deserializer does its magic, it maps all the elements of the response xml thereby updating our local variable. Here’s what I’m talking about. 1: [WebMethod(MessageName = "HelloAnyGalaxy")] 2: public string HelloGalaxy(ref string galaxyName) 3: { 4: string output = string.Format("Hello {0}", galaxyName); 5: if (galaxyName == "Andromeda") 6: { 7: galaxyName = string.Format("{0} (2.5 million light-years away)", galaxyName); 8: } 9: return output; 10: } This is how the request and response look like in soapUI. As I said above, the behavior is quite similar for WCF as well. But the catch comes when you have a one-way web methods / operation contracts. If you have an operation contract whose return type is void, is marked one-way and that has ref parameters then you’ll get an error message when you try to reference such a service. 1: [OperationContract(Name = "Sum", IsOneWay = true)] 2: void Sum(ref double arg1, ref double arg2); 3: 4: public void Sum(ref double arg1, ref double arg2) 5: { 6: arg1 += arg2; 7: } This is what I got when I did an update to my service reference: Makes sense, because a OneWay operation is… one-way – there’s no returning from this operation. You can also have a one-way web method: 1: [SoapDocumentMethod(OneWay = true)] 2: [WebMethod(MessageName = "HelloAnyGalaxy")] 3: public void HelloGalaxy(ref string galaxyName) This will throw an exception message similar to the one above when you try to update your web service reference. In the CLR space, there’s no such concept of a ‘one-way’ street! Yes, there’s void, but you very well can have ref parameters returned through such a method. Just a point here; although the ref/out concept sounds cool, it’s generally is a code-smell. The better approach is to always return an object that is composed of everything you need returned from a method. These are some of the differences that we need to bear when dealing with services that are different from our daily ‘CLR’ life.

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Easy Scaling in XAML (WPF)

- by Robert May

Ran into a problem that needed solving that was kind of fun. I’m not a XAML guru, and I’m sure there are better solutions, but I thought I’d share mine. The problem was this: Our designer had, appropriately, designed the system for a 1920 x 1080 screen resolution. This is for a full screen, touch screen device (think Kiosk), which has that resolution, but we also wanted to demo the device on a tablet (currently using the AWESOME Samsung tablet given out at Microsoft Build). When you’d run it on that tablet, things were ugly because it was at a lower resolution than the target device. Enter scaling. I did some research and found out that I probably just need to monkey with the LayoutTransform of some grid somewhere. This project is using MVVM and has a navigation container that we built that lives on a single root view. User controls are then loaded into that view as navigation occurs. In the parent grid of the root view, I added the following XAML: <Grid.LayoutTransform> <ScaleTransform ScaleX="{Binding ScaleWidth}" ScaleY="{Binding ScaleHeight}" /> </Grid.LayoutTransform> And then in the root View Model, I added the following code: /// <summary> /// The required design width /// </summary> private const double RequiredWidth = 1920; /// <summary> /// The required design height /// </summary> private const double RequiredHeight = 1080; /// <summary>Gets the ActualHeight</summary> public double ActualHeight { get { return this.View.ActualHeight; } } /// <summary>Gets the ActualWidth</summary> public double ActualWidth { get { return this.View.ActualWidth; } } /// <summary> /// Gets the scale for the height. /// </summary> public double ScaleHeight { get { return this.ActualHeight / RequiredHeight; } } /// <summary> /// Gets the scale for the width. /// </summary> public double ScaleWidth { get { return this.ActualWidth / RequiredWidth; } } Note that View.ActualWidth and View.ActualHeight are just pointing directly at FrameworkElement.ActualWidth and FrameworkElement.ActualHeight. That’s it. Just calculate the ratio and bind the scale transform to it. Hopefully you’ll find this useful. Technorati Tags: WPF,XAML

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Anatomy of a .NET Assembly - Custom attribute encoding

- by Simon Cooper

In my previous post, I covered how field, method, and other types of signatures are encoded in a .NET assembly. Custom attribute signatures differ quite a bit from these, which consequently affects attribute specifications in C#. Custom attribute specifications In C#, you can apply a custom attribute to a type or type member, specifying a constructor as well as the values of fields or properties on the attribute type: public class ExampleAttribute : Attribute { public ExampleAttribute(int ctorArg1, string ctorArg2) { ... } public Type ExampleType { get; set; } } [Example(5, "6", ExampleType = typeof(string))] public class C { ... } How does this specification actually get encoded and stored in an assembly? Specification blob values Custom attribute specification signatures use the same building blocks as other types of signatures; the ELEMENT_TYPE structure. However, they significantly differ from other types of signatures, in that the actual parameter values need to be stored along with type information. There are two types of specification arguments in a signature blob; fixed args and named args. Fixed args are the arguments to the attribute type constructor, named arguments are specified after the constructor arguments to provide a value to a field or property on the constructed attribute type (PropertyName = propValue) Values in an attribute blob are limited to one of the basic types (one of the number types, character, or boolean), a reference to a type, an enum (which, in .NET, has to use one of the integer types as a base representation), or arrays of any of those. Enums and the basic types are easy to store in a blob - you simply store the binary representation. Strings are stored starting with a compressed integer indicating the length of the string, followed by the UTF8 characters. Array values start with an integer indicating the number of elements in the array, then the item values concatentated together. Rather than using a coded token, Type values are stored using a string representing the type name and fully qualified assembly name (for example, MyNs.MyType, MyAssembly, Version=1.0.0.0, Culture=neutral, PublicKeyToken=0123456789abcdef). If the type is in the current assembly or mscorlib then just the type name can be used. This is probably done to prevent direct references between assemblies solely because of attribute specification arguments; assemblies can be loaded in the reflection-only context and attribute arguments still processed, without loading the entire assembly. Fixed and named arguments Each entry in the CustomAttribute metadata table contains a reference to the object the attribute is applied to, the attribute constructor, and the specification blob. The number and type of arguments to the constructor (the fixed args) can be worked out by the method signature referenced by the attribute constructor, and so the fixed args can simply be concatenated together in the blob without any extra type information. Named args are different. These specify the value to assign to a field or property once the attribute type has been constructed. In the CLR, fields and properties can be overloaded just on their type; different fields and properties can have the same name. Therefore, to uniquely identify a field or property you need: Whether it's a field or property (indicated using byte values 0x53 and 0x54, respectively) The field or property type The field or property name After the fixed arg values is a 2-byte number specifying the number of named args in the blob. Each named argument has the above information concatenated together, mostly using the basic ELEMENT_TYPE values, in the same way as a method or field signature. A Type argument is represented using the byte 0x50, and an enum argument is represented using the byte 0x55 followed by a string specifying the name and assembly of the enum type. The named argument property information is followed by the argument value, using the same encoding as fixed args. Boxed objects This would be all very well, were it not for object and object[]. Arguments and properties of type object allow a value of any allowed argument type to be specified. As a result, more information needs to be specified in the blob to interpret the argument bytes as the correct type. So, the argument value is simple prepended with the type of the value by specifying the ELEMENT_TYPE or name of the enum the value represents. For named arguments, a field or property of type object is represented using the byte 0x51, with the actual type specified in the argument value. Some examples... All property signatures start with the 2-byte value 0x0001. Similar to my previous post in the series, names in capitals correspond to a particular byte value in the ELEMENT_TYPE structure. For strings, I'll simply give the string value, rather than the length and UTF8 encoding in the actual blob. I'll be using the following enum and attribute types to demonstrate specification encodings: class AttrAttribute : Attribute { public AttrAttribute() {} public AttrAttribute(Type[] tArray) {} public AttrAttribute(object o) {} public AttrAttribute(MyEnum e) {} public AttrAttribute(ushort x, int y) {} public AttrAttribute(string str, Type type1, Type type2) {} public int Prop1 { get; set; } public object Prop2 { get; set; } public object[] ObjectArray; } enum MyEnum : int { Val1 = 1, Val2 = 2 } Now, some examples: Here, the the specification binds to the (ushort, int) attribute constructor, with fixed args only. The specification blob starts off with a prolog, followed by the two constructor arguments, then the number of named arguments (zero): [Attr(42, 84)] 0x0001 0x002a 0x00000054 0x0000 An example of string and type encoding: [Attr("MyString", typeof(Array), typeof(System.Windows.Forms.Form))] 0x0001 "MyString" "System.Array" "System.Windows.Forms.Form, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" 0x0000 As you can see, the full assembly specification of a type is only needed if the type isn't in the current assembly or mscorlib. Note, however, that the C# compiler currently chooses to fully-qualify mscorlib types anyway. An object argument (this binds to the object attribute constructor), and two named arguments (a null string is represented by 0xff and the empty string by 0x00) [Attr((ushort)40, Prop1 = 12, Prop2 = "")] 0x0001 U2 0x0028 0x0002 0x54 I4 "Prop1" 0x0000000c 0x54 0x51 "Prop2" STRING 0x00 Right, more complicated now. A type array as a fixed argument: [Attr(new[] { typeof(string), typeof(object) })] 0x0001 0x00000002 // the number of elements "System.String" "System.Object" 0x0000 An enum value, which is simply represented using the underlying value. The CLR works out that it's an enum using information in the attribute constructor signature: [Attr(MyEnum.Val1)] 0x0001 0x00000001 0x0000 And finally, a null array, and an object array as a named argument: [Attr((Type[])null, ObjectArray = new object[] { (byte)2, typeof(decimal), null, MyEnum.Val2 })] 0x0001 0xffffffff 0x0001 0x53 SZARRAY 0x51 "ObjectArray" 0x00000004 U1 0x02 0x50 "System.Decimal" STRING 0xff 0x55 "MyEnum" 0x00000002 As you'll notice, a null object is encoded as a null string value, and a null array is represented using a length of -1 (0xffffffff). How does this affect C#? So, we can now explain why the limits on attribute arguments are so strict in C#. Attribute specification blobs are limited to basic numbers, enums, types, and arrays. As you can see, this is because the raw CLR encoding can only accommodate those types. Special byte patterns have to be used to indicate object, string, Type, or enum values in named arguments; you can't specify an arbitary object type, as there isn't a generalised way of encoding the resulting value in the specification blob. In particular, decimal values can't be encoded, as it isn't a 'built-in' CLR type that has a native representation (you'll notice that decimal constants in C# programs are compiled as several integer arguments to DecimalConstantAttribute). Jagged arrays also aren't natively supported, although you can get around it by using an array as a value to an object argument: [Attr(new object[] { new object[] { new Type[] { typeof(string) } }, 42 })] Finally... Phew! That was a bit longer than I thought it would be. Custom attribute encodings are complicated! Hopefully this series has been an informative look at what exactly goes on inside a .NET assembly. In the next blog posts, I'll be carrying on with the 'Inside Red Gate' series.

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C# need help debugging socks5-connection attemp

- by Chuck

Hi, I've written the following code to (successfully) connect to a socks5 proxy. I send a user/pw auth and get an OK reply (0x00), but as soon as I tell the proxy to connect to whichever ip:port, it gives me 0x01 (general error). Socket socket5_proxy = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); IPEndPoint proxyEndPoint = new IPEndPoint(IPAddress.Parse("111.111.111.111"), 1080); // proxy ip, port. fake for posting purposes. socket5_proxy.Connect(proxyEndPoint); byte[] init_socks_command = new byte[4]; init_socks_command[0] = 0x05; init_socks_command[1] = 0x02; init_socks_command[2] = 0x00; init_socks_command[3] = 0x02; socket5_proxy.Send(init_socks_command); byte[] socket_response = new byte[2]; int bytes_recieved = socket5_proxy.Receive(socket_response, 2, SocketFlags.None); if (socket_response[1] == 0x02) { byte[] temp_bytes; string socks5_user = "foo"; string socks5_pass = "bar"; byte[] auth_socks_command = new byte[3 + socks5_user.Length + socks5_pass.Length]; auth_socks_command[0] = 0x05; auth_socks_command[1] = Convert.ToByte(socks5_user.Length); temp_bytes = Encoding.Default.GetBytes(socks5_user); temp_bytes.CopyTo(auth_socks_command, 2); auth_socks_command[2 + socks5_user.Length] = Convert.ToByte(socks5_pass.Length); temp_bytes = Encoding.Default.GetBytes(socks5_pass); temp_bytes.CopyTo(auth_socks_command, 3 + socks5_user.Length); socket5_proxy.Send(auth_socks_command); socket5_proxy.Receive(socket_response, 2, SocketFlags.None); if (socket_response[1] != 0x00) return; byte[] connect_socks_command = new byte[10]; connect_socks_command[0] = 0x05; connect_socks_command[1] = 0x02; // streaming connect_socks_command[2] = 0x00; connect_socks_command[3] = 0x01; // ipv4 temp_bytes = IPAddress.Parse("222.222.222.222").GetAddressBytes(); // target connection. fake ip, obviously temp_bytes.CopyTo(connect_socks_command, 4); byte[] portBytes = BitConverter.GetBytes(8888); connect_socks_command[8] = portBytes[0]; connect_socks_command[9] = portBytes[1]; socket5_proxy.Send(connect_socks_command); socket5_proxy.Receive(socket_response); if (socket_response[1] != 0x00) MessageBox.Show("Damn it"); // I always end here, 0x01 I've used this as a reference: http://en.wikipedia.org/wiki/SOCKS#SOCKS_5 Have I completely misunderstood something here? How I see it, I can connect to the socks5 fine. I can authenticate fine. But I/the proxy can't "do" anything? Yes, I know the proxy works. Yes, the target ip is available and yes the target port is open/responsive. I get 0x01 no matter what I try to connect to. Any help is VERY MUCH appreciated! Thanks, Chuck

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Why is there an implicit conversion from Float/Double to BigDecimal, but not from String?

- by soc

Although the situation of conversion from Doubles to BigDecimals has improved a bit compared to Java scala> new java.math.BigDecimal(0.2) res0: java.math.BigDecimal = 0.20000000000000001110223024625156... scala> BigDecimal(0.2) res1: scala.math.BigDecimal = 0.2 and things like val numbers: List[BigDecimal] = List(1.2, 3.2, 0.7, 0.8, 1.1) work really well, wouldn't it be reasonable to have an implicit conversion like implicit def String2BigDecimal(s: String) = BigDecimal(s) available by default which can convert Strings to BigDecimals like this? val numbers: List[BigDecimal] = List("1.2", "3.2", "0.7", "0.8", "1.1") Or am I missing something and Scala resolved all "problems" of Java with using the BigDecimal constructor with a floating point value instead of a String, and BigDecimal(String) is basically not needed anymore in Scala?

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Why does BeginReceiveFrom never time out?

- by James Hugard

I am writing an asynchronous Ping using Raw Sockets in F#, to enable parallel requests using as few threads as possible ("System.Net.NetworkInformation.Ping" appears to use one thread per request, but have not tested this... also am interested in using F# async workflows). The synchronous version below correctly times out when the target host does not exist/respond, but the asynchronous version hangs. Both work when the host does respond... Any ideas? (note: the process must run as Admin for this code to work) This throws a timeout: let result = Ping.Ping ( IPAddress.Parse( "192.168.33.22" ), 1000 ) However, this hangs: let result = Ping.PingAsync ( IPAddress.Parse( "192.168.33.22" ), 1000 ) |> Async.RunSynchronously Here's the code... module Ping open System open System.Net open System.Net.Sockets open System.Threading //---- ICMP Packet Classes type IcmpMessage (t : byte) = let mutable m_type = t let mutable m_code = 0uy let mutable m_checksum = 0us member this.Type with get() = m_type member this.Code with get() = m_code member this.Checksum = m_checksum abstract Bytes : byte array default this.Bytes with get() = [| m_type m_code byte(m_checksum) byte(m_checksum >>> 8) |] member this.GetChecksum() = let mutable sum = 0ul let bytes = this.Bytes let mutable i = 0 // Sum up uint16s while i < bytes.Length - 1 do sum <- sum + uint32(BitConverter.ToUInt16( bytes, i )) i <- i + 2 // Add in last byte, if an odd size buffer if i <> bytes.Length then sum <- sum + uint32(bytes.[i]) // Shuffle the bits sum <- (sum >>> 16) + (sum &&& 0xFFFFul) sum <- sum + (sum >>> 16) sum <- ~~~sum uint16(sum) member this.UpdateChecksum() = m_checksum <- this.GetChecksum() type InformationMessage (t : byte) = inherit IcmpMessage(t) let mutable m_identifier = 0us let mutable m_sequenceNumber = 0us member this.Identifier = m_identifier member this.SequenceNumber = m_sequenceNumber override this.Bytes with get() = Array.append (base.Bytes) [| byte(m_identifier) byte(m_identifier >>> 8) byte(m_sequenceNumber) byte(m_sequenceNumber >>> 8) |] type EchoMessage() = inherit InformationMessage( 8uy ) let mutable m_data = Array.create 32 32uy do base.UpdateChecksum() member this.Data with get() = m_data and set(d) = m_data <- d this.UpdateChecksum() override this.Bytes with get() = Array.append (base.Bytes) (this.Data) //---- Synchronous Ping let Ping (host : IPAddress, timeout : int ) = let mutable ep = new IPEndPoint( host, 0 ) let socket = new Socket( AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.SendTimeout, timeout ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, timeout ) let packet = EchoMessage() let mutable buffer = packet.Bytes try if socket.SendTo( buffer, ep ) <= 0 then raise (SocketException()) buffer <- Array.create (buffer.Length + 20) 0uy let mutable epr = ep :> EndPoint if socket.ReceiveFrom( buffer, &epr ) <= 0 then raise (SocketException()) finally socket.Close() buffer //---- Entensions to the F# Async class to allow up to 5 paramters (not just 3) type Async with static member FromBeginEnd(arg1,arg2,arg3,arg4,beginAction,endAction,?cancelAction): Async<'T> = Async.FromBeginEnd((fun (iar,state) -> beginAction(arg1,arg2,arg3,arg4,iar,state)), endAction, ?cancelAction=cancelAction) static member FromBeginEnd(arg1,arg2,arg3,arg4,arg5,beginAction,endAction,?cancelAction): Async<'T> = Async.FromBeginEnd((fun (iar,state) -> beginAction(arg1,arg2,arg3,arg4,arg5,iar,state)), endAction, ?cancelAction=cancelAction) //---- Extensions to the Socket class to provide async SendTo and ReceiveFrom type System.Net.Sockets.Socket with member this.AsyncSendTo( buffer, offset, size, socketFlags, remoteEP ) = Async.FromBeginEnd( buffer, offset, size, socketFlags, remoteEP, this.BeginSendTo, this.EndSendTo ) member this.AsyncReceiveFrom( buffer, offset, size, socketFlags, remoteEP ) = Async.FromBeginEnd( buffer, offset, size, socketFlags, remoteEP, this.BeginReceiveFrom, (fun asyncResult -> this.EndReceiveFrom(asyncResult, remoteEP) ) ) //---- Asynchronous Ping let PingAsync (host : IPAddress, timeout : int ) = async { let ep = IPEndPoint( host, 0 ) use socket = new Socket( AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.SendTimeout, timeout ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, timeout ) let packet = EchoMessage() let outbuffer = packet.Bytes try let! result = socket.AsyncSendTo( outbuffer, 0, outbuffer.Length, SocketFlags.None, ep ) if result <= 0 then raise (SocketException()) let epr = ref (ep :> EndPoint) let inbuffer = Array.create (outbuffer.Length + 256) 0uy let! result = socket.AsyncReceiveFrom( inbuffer, 0, inbuffer.Length, SocketFlags.None, epr ) if result <= 0 then raise (SocketException()) return inbuffer finally socket.Close() }

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