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• How do i get (is it possible to) a reference to the class that creates an instance of another class.

  - by Cadde

  Odd situation... I need to create a new instance of a class that needs a member of the calling class. But i can't pass a reference to the calling class through the constructor. The solution i am looking for is something like this: Public Class ChildClass Public Sub New(args) _MyMember = GetMemberFromCallingClass() ... ... End Sub End Class I want this to work without having to manually pass any references or variables from the calling class to the new instance of ChildClass. Is this possible and if so, what should i look at to make this part of my code.

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• Checking for a session variable... returns (Object reference not set to an instance of an object.)

  - by Chocol8

  In the Session_Start i have Sub Session_Start(ByVal sender As Object, ByVal e As EventArgs) Session("login") = False End Sub and in a custom .aspx page i included the following... Public ReadOnly Property GetLoginState() As Boolean Get If Current.Session("login") Is Nothing Then Current.Session("login") = False End If Return Current.Session("login") End Get End Property Why i am getting error the error Object reference not set to an instance of an object. at line If Current.Session("login") Is Nothing Then while checking for the login state as follows? If GetLogin = False Then 'Do something End if I mean i have already created the instance on the Session_Start... Haven't i? What am i doing wrong here?

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• Can we overload a function based on only whether a parameter is a value or a reference?

  - by skydoor

  I got the answer NO! Because passing by value and passing by reference looks identical to the caller. However, the code below compiles right class A { public: void f(int i) {} void f(int& i) {} }; But when I try to use it, there is compile error. int main () { A a; int i = 9; int& j = i; a.f(1); a.f(i); a.f(j); return 0; } Why does not the compiler disable it even without knowing it is going to be used?

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• How Do I Reference An Element By Name With [] Brackets In It?

  - by user384030

  How do you reference a element in jquery BY NAME that has the [] in it. <select name="values[]" multiple="true"> <option value="1">1</option> <option value="2">2</option> <option value="2">2</option> </select> <script type="text/javascript"> $('[name=values[]]'); </script> this should grab the element, but it does not work, I believe the [] in the name is messing it up, escaping it doesn't seem to work either. I can't figure out what I'm doing wrong

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• C#/.NET Little Pitfalls: The Dangers of Casting Boxed Values

  - by James Michael Hare

  Starting a new series to parallel the Little Wonders series.  In this series, I will examine some of the small pitfalls that can occasionally trip up developers. Introduction: Of Casts and Conversions What happens when we try to assign from an int and a double and vice-versa? 1: double pi = 3.14; 2: int theAnswer = 42; 3:  4: // implicit widening conversion, compiles! 5: double doubleAnswer = theAnswer; 6:  7: // implicit narrowing conversion, compiler error! 8: int intPi = pi; As you can see from the comments above, a conversion from a value type where there is no potential data loss is can be done with an implicit conversion.  However, when converting from one value type to another may result in a loss of data, you must make the conversion explicit so the compiler knows you accept this risk.  That is why the conversion from double to int will not compile with an implicit conversion, we can make the conversion explicit by adding a cast: 1: // explicit narrowing conversion using a cast, compiler 2: // succeeds, but results may have data loss: 3: int intPi = (int)pi; So for value types, the conversions (implicit and explicit) both convert the original value to a new value of the given type.  With widening and narrowing references, however, this is not the case.  Converting reference types is a bit different from converting value types.  First of all when you perform a widening or narrowing you don’t really convert the instance of the object, you just convert the reference itself to the wider or narrower reference type, but both the original and new reference type both refer back to the same object. Secondly, widening and narrowing for reference types refers the going down and up the class hierarchy instead of referring to precision as in value types.  That is, a narrowing conversion for a reference type means you are going down the class hierarchy (for example from Shape to Square) whereas a widening conversion means you are going up the class hierarchy (from Square to Shape).  1: var square = new Square(); 2:  3: // implicitly convers because all squares are shapes 4: // (that is, all subclasses can be referenced by a superclass reference) 5: Shape myShape = square; 6:  7: // implicit conversion not possible, not all shapes are squares! 8: // (that is, not all superclasses can be referenced by a subclass reference) 9: Square mySquare = (Square) myShape; So we had to cast the Shape back to Square because at that point the compiler has no way of knowing until runtime whether the Shape in question is truly a Square.  But, because the compiler knows that it’s possible for a Shape to be a Square, it will compile.  However, if the object referenced by myShape is not truly a Square at runtime, you will get an invalid cast exception. Of course, there are other forms of conversions as well such as user-specified conversions and helper class conversions which are beyond the scope of this post.  The main thing we want to focus on is this seemingly innocuous casting method of widening and narrowing conversions that we come to depend on every day and, in some cases, can bite us if we don’t fully understand what is going on!  The Pitfall: Conversions on Boxed Value Types Can Fail What if you saw the following code and – knowing nothing else – you were asked if it was legal or not, what would you think: 1: // assuming x is defined above this and this 2: // assignment is syntactically legal. 3: x = 3.14; 4:  5: // convert 3.14 to int. 6: int truncated = (int)x; You may think that since x is obviously a double (can’t be a float) because 3.14 is a double literal, but this is inaccurate.  Our x could also be dynamic and this would work as well, or there could be user-defined conversions in play.  But there is another, even simpler option that can often bite us: what if x is object? 1: object x; 2:  3: x = 3.14; 4:  5: int truncated = (int) x; On the surface, this seems fine.  We have a double and we place it into an object which can be done implicitly through boxing (no cast) because all types inherit from object.  Then we cast it to int.  This theoretically should be possible because we know we can explicitly convert a double to an int through a conversion process which involves truncation. But here’s the pitfall: when casting an object to another type, we are casting a reference type, not a value type!  This means that it will attempt to see at runtime if the value boxed and referred to by x is of type int or derived from type int.  Since it obviously isn’t (it’s a double after all) we get an invalid cast exception! Now, you may say this looks awfully contrived, but in truth we can run into this a lot if we’re not careful.  Consider using an IDataReader to read from a database, and then attempting to select a result row of a particular column type: 1: using (var connection = new SqlConnection("some connection string")) 2: using (var command = new SqlCommand("select * from employee", connection)) 3: using (var reader = command.ExecuteReader()) 4: { 5: while (reader.Read()) 6: { 7: // if the salary is not an int32 in the SQL database, this is an error! 8: // doesn't matter if short, long, double, float, reader [] returns object! 9: total += (int) reader["annual_salary"]; 10: } 11: } Notice that since the reader indexer returns object, if we attempt to convert using a cast to a type, we have to make darn sure we use the true, actual type or this will fail!  If the SQL database column is a double, float, short, etc this will fail at runtime with an invalid cast exception because it attempts to convert the object reference! So, how do you get around this?  There are two ways, you could first cast the object to its actual type (double), and then do a narrowing cast to on the value to int.  Or you could use a helper class like Convert which analyzes the actual run-time type and will perform a conversion as long as the type implements IConvertible. 1: object x; 2:  3: x = 3.14; 4:  5: // if you want to cast, must cast out of object to double, then 6: // cast convert. 7: int truncated = (int)(double) x; 8:  9: // or you can call a helper class like Convert which examines runtime 10: // type of the value being converted 11: int anotherTruncated = Convert.ToInt32(x); Summary You should always be careful when performing a conversion cast from values boxed in object that you are actually casting to the true type (or a sub-type). Since casting from object is a widening of the reference, be careful that you either know the exact, explicit type you expect to be held in the object, or instead avoid the cast and use a helper class to perform a safe conversion to the type you desire. Technorati Tags: C#,.NET,Pitfalls,Little Pitfalls,BlackRabbitCoder

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• How to reference a Domain Controller out of the Local Network?

  - by Adrian

  We have multiple servers scattered over different hosting providers. For learning, experimenting and, ultimately, production purposes, I set one of them as a Domain Controller. That went well, most of our services are now authenticating via AD, which helps us a lot. What I want to do now is to simplify the authentication for the multiple servers, by making each of them look at the Domain Controller. This way, our Devs can log into (Remote Desktop) the multiple servers with the same credentials from AD. I know I have to configure each server to look at the Domain Controller. But when I try to add the Domain Controller to the Computer, it cannot find it, although the Domain Controller address is a valid, reachable internet sub-domain (as in "ad.ourcompany.com"). This is the detailed error message: Note: This information is intended for a network administrator. If you are not your network's administrator, notify the administrator that you received this information, which has been recorded in the file C:\Windows\debug\dcdiag.txt. The following error occurred when DNS was queried for the service location (SRV) resource record used to locate an Active Directory Domain Controller for domain ad.ourcompany.com: The error was: "DNS name does not exist." (error code 0x0000232B RCODE_NAME_ERROR) The query was for the SRV record for _ldap._tcp.dc._msdcs.ad.ourcompany.com Common causes of this error include the following: - The DNS SRV records required to locate a AD DC for the domain are not registered in DNS. These records are registered with a DNS server automatically when a AD DC is added to a domain. They are updated by the AD DC at set intervals. This computer is configured to use DNS servers with the following IP addresses: 109.188.207.9 109.188.207.10 - One or more of the following zones do not include delegation to its child zone: ad.ourcompany.com ourcompany.com com . (the root zone) For information about correcting this problem, click Help. What am I missing? I'm an experienced Dev, but a newbie Sysdamin experimenting with new stuff. Disclaimer All IP addresses and domains/subdomains were changed to preserve security. If by any chance you still can see private information, please let me know so that I can change it.

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• Can you reference an entire column in OpenOffice Calc (like A:A in Excel)?

  - by Andy

  I'd like to refer to an entire column, like you can in Excel by using A:A. I found a discussion on the openoffice.org forums which is a few years old, and suggests there is/was no neat way to do it. The options presented are Use A1:A65536. Use OFFSET($A$1;0;0;65536;1) as the previous range may get altered if you insert or remove rows. Use Data - Define Range... to name the column range (but which for me still just equates to $A$1:$A$1048576). These approaches seem over-complicated and still don't achieve my goal perfectly. Does anyone know of a way? Thanks, Andy

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• Is there a reference to all Windows "errorlevel" by command?

  - by Tommy

  Looking for a page that defines all error levels, by command. Thanks.

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• How do I reference the value of a constructed environment variable in a loop?

  - by Rob Spieldenner

  What I'm trying to do is loop over environment variables. I have a number of installs that change and each install has 3 IPs to push files to and run scripts on, and I want to automate this as much as possible (so that I only have to modify a file that I'll source with the environment variables). The following is a simplified version that once I figure out I can solve my problem. So given in my.props: COUNT=2 A_0=foo B_0=bar A_1=fizz B_1=buzz I want to fill in the for loop in the following script #!/bin/bash . <path>/my.props for ((i=0; i < COUNT; i++)) do <script here> done So that I can get the values from the environment variables. Like the following(but that actually work): echo $A_$i $B_$i or A=A_$i B=B_$i echo $A $B returns foo bar then fizz buzz

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• Good tutorial / book / reference material for Linux Configuration Files.

  - by claws

  Hello, I'm a windows user recently moved to linux. The main problem is that not all settings can be changed with GUI interfaces. I like the idea of configuration files. But the problem is figuring out which configuration files must be edited to change certain setting. Is there any good (or best :D) material (book/article/ref sheet) which explains these things.

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• Excel - Dynamic row reference based on the row I paste a formula into?

  - by michaelmichael

  I have a simple, oft-used formula that I paste as plain text into spreadsheets I receive. It looks something like this: =IF(D8="FOO", "BAR", "BAZ") It looks in D8 for the word "FOO". If it finds it it will show "BAR". If it doesn't it will show "BAZ" It works great. The problem is I have to paste this formula as plain text into many spreadsheets. It should ALWAYS look in column D for "FOO", however I don't always want it to look in row 8. I'd like it to look at whatever row I'm pasting it into. For example, if I pasted the above formula into row 25, say, I would like it to automatically change to this: =IF(D25="FOO", "BAR", "BAZ") Is there any way to achieve this?

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• How to reference or vlookup a list of values based on a comma separated list of column references within a cell in excel?

  - by glallen

  I want to do a vlookup (or similar) against a column which is a list of values. This works fine for looking up a value from a single row, but I want to be able to look up multiple rows, sum the results, and divide by the number of rows referenced. For example: A B C D E F G [----given values----------------] [Work/Auth] [sum(vlookup(each(G),table,5)) /count(G)] [given vals] 1 Item Authorized OnHand Working Operational% DependencyOR% Dependencies 2 A 1 1 1 1 .55 B 3 B 10 5 5 .50 .55 C,D 4 C 100 75 50 .50 .60 D 5 D 10 10 6 .60 1 I want to be able to show an Operational Rate, and an operational rate of the systems each system depends on (F). In order to get a value for F, I want to sum over each value in column-E that was referenced by a dependency in column-G then divide by the number of dependencies in G. Column-G can have varying lengths, and will be a comma separated list of values from column-A. Is there any way to do this in excel?

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• Troubleshooting SQL Azure Connectivity

  - by kaleidoscope

  Technorati Tags: Rituraj,Connectivity Issues with SQL Azure Troubleshooting SQL Azure Connectivity How to resolve some of the common connectivity error messages that you would see while connecting to SQL Azure A transport-level error has occurred when receiving results from the server. (Provider: TCP Provider, error: 0 - An existing connection was forcibly closed by the remote host.) System.Data.SqlClient.SqlException: Timeout expired.  The timeout period elapsed prior to completion of the operation or the server is not responding. The statement has been terminated. An error has occurred while establishing a connection to the server. When connecting to SQL Server 2005, this failure may be caused by the fact that under the default settings SQL Server does not allow remote connections Error: Microsoft SQL Native Client: Unable to complete login process due to delay in opening server connection. A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond. Some troubleshooting tips a) Verify Azure Firewall Settings and Service Availability     Reference: SQL Azure Firewall - http://msdn.microsoft.com/en-us/library/ee621782.aspx b) Verify that you can reach our Virtual IP     Reference: Telnet Troubleshooting Guide - http://technet.microsoft.com/en-us/library/cc753360(WS.10).aspx    Reference: How to Use TRACERT to Troubleshoot TCP/IP Problems in Windows - http://support.microsoft.com/kb/314868 c) Windows Firewall on the local machine     Frequently Asked Questions - http://msdn.microsoft.com/en-us/library/bb736261(VS.85).aspx     Reference: Windows Firewall with Advanced Security Getting Started Guide - http://technet.microsoft.com/en-us/library/cc748991(WS.10).aspx d) Other Firewall products     Reference: http://www.whatismyip.com/ e) Generate a Network Trace using Microsoft Network Monitor tool    Reference: How to capture network traffic with Network Monitor - http://support.microsoft.com/kb/148942 f) SQL Azure Denial of Service (DOS) Guard SQL Azure utilizes techniques to prevent denial of service attacks. If your connection is getting reset by our service due to a potential DOS attack you would  be able to see a three way handshake established and then a RESET in your network trace.

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• links for 2010-12-10

  - by Bob Rhubart

  Oracle VM Blade Cluster Reference Configuration (InfraRed) "All components listed in the reference configuration have been tested together by Oracle, reducing the need for customer testing and the time-consuming and complex effort of designing and deploying a stable configuration." -- Ferhat Hatay (tags: oracle virtualization clustering) White Paper: Accelerating Deployment of Virtualized Infrastructures with the Oracle VM Blade Cluster Reference Configuration  The Oracle VM blade cluster reference configuration described in this paper provides a complete and fully tested virtualized stack that can reduce deployment time by weeks or months while also reducing risk and improving application performance. (tags: oracle otn virtualization infrastructure) White Paper: Best Practices and Guidelines for Deploying the Oracle VM Blade Cluster Reference Configuration This paper provides recommendations and best practices for optimizing virtualization infrastructures when deploying the Oracle VM blade cluster reference configuration.  (tags: oracle otn virtualization clustering) Your Most Familiar Processes - Rethink before using E2.0 | Enterprise 2.0 Blogs "Imagine what gains your organization could have by asking basic questions and reviewing your familiar processes before setting up even the most fundamental E2.0 technologies to support them!" -- John Brunswick (tags: oracle enterprise2.0 otn) Oracle's Global Single Schema (Oracle Master Data Management) "The success of all business processes depends on the availability of accurate master data. Clearly, the solution to this problem is to consolidate all the master data an organization uses to run its business." -- David Butler (tags: oracle otn mdm entarch businessprocess) One step further towards proven results: IT Strategies from Oracle Oracle ACE Douwe Pieter van den Bos shares his thoughts on "IT Strategies from Oracle" in this Google translation of his original Dutch post. (tags: oracle itso entarch) The Underground Oracle VM Manual Just in time for the holidays! Roddy Rodstein's epic 354-page manual is now available in a single pdf.. (tags: oracle otn virtualization oraclevm)

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• Azure git deployment - missing references in 2nd assembly

  - by Dan

  I'm trying to setup Bitbucket deployment to an Azure website. I successfully have Bitbucket and Azure linked, but when I push to Bitbucket, I get the following error on the Azure site: If I click on 'View Log', it shows the following compile errors: D:\Windows\Microsoft.NET\Framework\v4.0.30319\Microsoft.Common.targets(1578,5): warning MSB3245: Could not resolve this reference. Could not locate the assembly "System.Web.Mvc, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL". Check to make sure the assembly exists on disk. If this reference is required by your code, you may get compilation errors. [C:\DWASFiles\Sites\<projname>\VirtualDirectory0\site\repository\<projname>.Common\<projname>.Common.csproj] D:\Windows\Microsoft.NET\Framework\v4.0.30319\Microsoft.Common.targets(1578,5): warning MSB3245: Could not resolve this reference. Could not locate the assembly "WebMatrix.WebData, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL". Check to make sure the assembly exists on disk. If this reference is required by your code, you may get compilation errors. [C:\DWASFiles\Sites\<projname>\VirtualDirectory0\site\repository\<projname>.Common\<projname>.Common.csproj] CustomMembershipProvider.cs(5,7): error CS0246: The type or namespace name 'WebMatrix' could not be found (are you missing a using directive or an assembly reference?) [C:\DWASFiles\Sites\<projname>\VirtualDirectory0\site\repository\<projname>.Common\<projname>.Common.csproj] CustomMembershipProvider.cs(9,38): error CS0246: The type or namespace name 'ExtendedMembershipProvider' could not be found (are you missing a using directive or an assembly reference?) [C:\DWASFiles\Sites\<projname>\VirtualDirectory0\site\repository\<projname>.Common\<projname>.Common.csproj] Models\AccountModels.cs(3,18): error CS0234: The type or namespace name 'Mvc' does not exist in the namespace 'System.Web' (are you missing an assembly reference?) [C:\DWASFiles\Sites\<projname>\VirtualDirectory0\site\repository\<projname>.Common\<projname>.Common.csproj] CustomMembershipProvider.cs(198,37): error CS0246: The type or namespace name 'OAuthAccountData' could not be found (are you missing a using directive or an assembly reference?) [C:\DWASFiles\Sites\<projname>\VirtualDirectory0\site\repository\<projname>.Common\<projname>.Common.csproj] Models\AccountModels.cs(40,10): error CS0246: The type or namespace name 'Compare' could not be found (are you missing a using directive or an assembly reference?) [C:\DWASFiles\Sites\<projname>\VirtualDirectory0\site\repository\<projname>.Common\<projname>.Common.csproj] Models\AccountModels.cs(40,10): error CS0246: The type or namespace name 'CompareAttribute' could not be found (are you missing a using directive or an assembly reference?) [C:\DWASFiles\Sites\<projname>\VirtualDirectory0\site\repository\<projname>.Common\<projname>.Common.csproj] Models\AccountModels.cs(73,10): error CS0246: The type or namespace name 'Compare' could not be found (are you missing a using directive or an assembly reference?) [C:\DWASFiles\Sites\<projname>\VirtualDirectory0\site\repository\<projname>.Common\<projname>.Common.csproj] Models\AccountModels.cs(73,10): error CS0246: The type or namespace name 'CompareAttribute' could not be found (are you missing a using directive or an assembly reference?) [C:\DWASFiles\Sites\<projname>\VirtualDirectory0\site\repository\<projname>.Common\<projname>.Common.csproj] Note that these compile errors are against another assembly in my project (the assembly where I put the business logic). When Googling, the only mention I found was about having to set the "local copy" flag to true for those references. I've tried this, but still got the same errors. This all compiles fine locally. Any ideas?

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• How to write a Media Center plugin like the Netflix plugin? Source code/reference samples?

  - by Vin

  I am looking to write a Windows Media Center plugin just like the Netflix WMC plugin. Once logged in, I know the streaming urls that I need to hook in to. Any source code, reference samples would be great. Found one on codeplex for swedish TV channels, but right now it's not working for some reason... Previously asked the following question, with no answers, so updated with a question asked in a easy to relate fashion Host a streaming video in my client, from a streaming url that is behind a login session? I am building a Silverlight 4 desktop client to show streaming video from a site that is login based. So that website has a Silverlight player that does streaming video, the player is behind a login sesion, so just by getting the url from fiddler and trying to play it in my Silverlight 4 desktop client won't work. Actually after that, I want to build a Windows Media Center plugin to build a Netflix-like client, that allows login through WMC and then allows you to watch streaming video. Any pointers on how to go about doing any of this?

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• How can I add a link with a UID from a User Reference from a table in Drupal Views

  - by pduncan

  I have the following in Drupal 6: A Master CCK type which contains a User reference field and other fields. There will only be one record per user here. A View of this CCK, shown as a table, with one of the fields being the user ref from the CCK type. This field is initially shown as a user name, linking to the user profile. A Second CCK type which can have several pieces of data about a particular user. A View for this CCK type, displaying information as a table. It takes a user id as an argument (an integer) I want to click on the user name in the master view, and be directed to the detail view for this user. To do this, I tried selecting 'Output this field as a link' on the user field. The thing available for me to replace are: Fields * [field_my_user_ref_uid_1] == Content: User (field_my_user_ref) Arguments * %1 == User: Uid However, the [field_my_user_ref_uid_1] element is replaced by the user name, and %1 seems to get replaced with an empty string. How can I put the user id in here?

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• object reference not set to an instance of object exception coming at runtime.

  - by amby

  Hi, I am getting this error at runtime: object reference not set to an instance of object my question is that am i using stringbuilder array correctly here. Because I am new in C#. and i think its the problem with my stringbuilder array. Below is the code: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Services; using System.Web.UI; using System.Web.UI.WebControls; using System.Data; using System.Text; using System.Web.Script.Serialization; using System.Web.Script.Services; using System.Collections; public partial class Testing : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { } [WebMethod] public static string SendMessage() { try { al2c00.ldap ws = new al2c00.ldap(); Hashtable htPeople = new Hashtable(); //DataTable dt = ws.GetEmployeeDetailsBy_NTID("650FA25C-9561-430B-B757-835D043EA5E5", "john"); StringBuilder[] empDetails = new StringBuilder[100]; string num = "ambreen"; empDetails[0].Append("amby"); num = empDetails[0].ToString(); htPeople.Add("bellempposreport", num); JavaScriptSerializer jss = new JavaScriptSerializer(); string output = jss.Serialize(htPeople); return output; } catch(Exception ex) { return ex.Message + "-" + ex.StackTrace; } } } please reply me what i am doing wrong here.

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• How can I determine if an object or reference has a valid string coercion?

  - by Ether

  I've run into a situation (while logging various data changes) where I need to determine if a reference has a valid string coercion (e.g. can properly be printed into a log or stored in a database). There isn't anything in Scalar::Util to do this, so I have cobbled together something using other methods in that library: use strict; use warnings; use Scalar::Util qw(reftype refaddr); sub has_string_coercion { my $value = shift; my $as_string = "$value"; my $ref = ref $value; my $reftype = reftype $value; my $refaddr = sprintf "0x%x", refaddr $value; if ($ref eq $reftype) { # base-type references stringify as REF(0xADDR) return $as_string !~ /^${ref}\(${refaddr}\)$/; } else { # blessed objects stringify as REF=REFTYPE(0xADDR) return $as_string !~ /^${ref}=${reftype}\(${refaddr}\)$/; } } # Example: use DateTime; my $ref1 = DateTime->now; my $ref2 = \'foo'; print "DateTime has coercion: " . has_string_coercion($ref1) . "\n\n"; print "scalar ref has coercion: " . has_string_coercion($ref2) . "\n"; However, I suspect there might be a better way of determining this by inspecting the guts of the variable in some way. How can this be done better?

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• WCF and ASP.NET - Server.Execute throwing object reference not set to an instance of an object

  - by user208662

  Hello, I have an ASP.NET page that calls to a WCF service. This WCF service uses a BackgroundWorker to asynchronously create an ASP.NET page on my server. Oddly, when I execute the WCF Service [OperationContract] [WebInvoke(Method = "POST", BodyStyle = WebMessageBodyStyle.WrappedRequest, RequestFormat = WebMessageFormat.Json, ResponseFormat = WebMessageFormat.Json)] public void PostRequest(string comments) { // Do stuff // If everything went o.k. asynchronously render a page on the server. I do not want to // block the caller while this is occurring. BackgroundWorker myWorker = new BackgroundWorker(); myWorker.DoWork += new DoWorkEventHandler(myWorker_DoWork); myWorker.RunWorkerAsync(HttpContext.Current); } private void myWorker_DoWork(object sender, DoWorkEventArgs e) { // Set the current context so we can render the page via Server.Execute HttpContext context = (HttpContext)(e.Argument); HttpContext.Current = context; // Retrieve the url to the page string applicationPath = context.Request.ApplicationPath; string sourceUrl = applicationPath + "/log.aspx"; string targetDirectory = currentContext.Server.MapPath("/logs/"); // Execute the other page and load its contents using (StringWriter stringWriter = new StringWriter()) { // Write the contents out to the target url // NOTE: THIS IS WHERE MY ERROR OCCURS currentContext.Server.Execute(sourceUrl, stringWriter); // Prepare to write out the result of the log targetPath = targetDirectory + "/" + DateTime.Now.ToShortDateString() + ".aspx"; using (StreamWriter streamWriter = new StreamWriter(targetPath, false)) { // Write out the content to the file sb.Append(stringWriter.ToString()); streamWriter.Write(sb.ToString()); } } } Oddly, when the currentContext.Server.Execute method is executed, it throws an "object reference not set to an instance of an object" error. The reason this is so strange is because I can look at the currentContext properties in the watch window. In addition, Server is not null. Because of this, I have no idea where this error is coming from. Can someone point me in the correct direction of what the cause of this could be? Thank you!

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• Copy a multi-dimentional array by Value (not by reference) in PHP.

  - by Simon R

  Language: PHP I have a form which asks users for their educational details, course details and technical details. When the form is submitted the page goes to a different page to run processes on the information and save parts to a database. HOWEVER(!) I then need to return the page back to the original page, where having access to the original post information is needed. I thought it would be simple to copy (by value) the multi-dimensional (md) $_POST array to $_SESSION['post'] session_start(); $_SESSION['post'] = $_POST; However this only appears to place the top level of the array into $_SESSION['post'] not doing anything with the children/sub-arrays. An abbreviated form of the md $_POST array is as follows: Array ( [formid] = 2 [edu] = Array ( ['id'] = Array ( [1] = new_1 [2] = new_2 ) ['nameOfInstitution'] = Array ( [1] = 1 [2] = 2 ) ['qualification'] = Array ( [1] = blah [2] = blah ) ['grade'] = Array ( [1] = blah [2] = blah ) ) [vID] = 61 [Submit] = Save and Continue ) If I echo $_SESSION['post']['formid'] it writes "2", and if I echo $_SESSION['post']['edu'] it returns "Array". If I check that edu is an array (is_array($_SESSION['post']['edu])) it returns true. If I echo $_SESSION['post']['edu']['id'] it returns array, but when checked (is_array($_SESSION['post']['edu]['id'])) it returns false and I cannot echo out any of the elements. How do I successfully copy (by value, not by reference) the whole array (including its children) to an new array?

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• Get reference to all instances of jquery ui widget?

  - by Hailwood

  I am writing a jquery UI widget that simply wraps the bootstrap popover plugin, In the widget you can pass in the option 'singular', if this is passed in then it should call a function of all other instances of the plugin. something like $('#one').myWidget(); $('#two').myWidget(); $('#three').myWidget(); $('#four').myWidget(); $('#one').myWidget('show'); //stuff from widget one is now visible $('#two').myWidget('show'); //stuff from widget one and two are now visible $('#three').myWidget('show'); //stuff from widget one, two and three are now visible $('#two').myWidget('hide'); //stuff from widget one and three are now visible $('#four').myWidget('show', {singular:true}); //stuff from widget four is now visible So, I imagine the show function looking like: show: function(options){ options = options || {}; if(options.singular){ var instances = '????'; // how do I get all instances? $.each(instances, function(i, o){ o.myWidget('hide'); }); } this.element.popover('show'); } So, question being, how would I get a reference to all elements that have the myWidget widget on them?

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• How to safely transfer reference to object across window?

  - by Morgan Cheng

  I'm debugging a web application. Javasript in one window create one object and use it as argument to invoke global method in another window. Pseudo code is like below. var obj = new Foo(); anotherWin.bar(obj); In anotherWin, the argument is stored in global variable. var g_obj; function bar(obj) { g_obj = obj; ... } When other function tries to reference g_obj.Id, it throws exception "Cannot evaluate expression". This happens in IE8.0.7600.16385 on Windows 7. In Visual Studio debugger, when this exception happens, the g_obj shows as {...} It looks all its properties are lost. Perhaps the root reason is the object is created in one window but only referenced in another window. The object might be garbage-collected at any time. Is there any way to work around this?

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• How is it legal to reference an undefined type inside a structure?

  - by paxdiablo

  As part of answering another question, I came across a piece of code like this, which gcc compiles without complaint. typedef struct { struct xyz *z; } xyz; int main (void) { return 0; } This is the means I've always used to construct types that point to themselves (e.g., linked lists) but I've always thought you had to name the struct so you could use self-reference. In other words, you couldn't use xyz *z within the structure because the typedef is not yet complete at that point. But this particular sample does not name the structure and it still compiles. I thought originally there was some black magic going on in the compiler that automatically translated the above code because the structure and typedef names were the same. But this little beauty works as well: typedef struct { struct NOTHING_LIKE_xyz *z; } xyz; What am I missing here? This seems a clear violation since there is no struct NOTHING_LIKE_xyz type defined anywhere. When I change it from a pointer to an actual type, I get the expected error: typedef struct { struct NOTHING_LIKE_xyz z; } xyz; qqq.c:2: error: field `z' has incomplete type Also, when I remove the struct, I get an error (parse error before "NOTHING ...). Is this allowed in ISO C?

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• Object reference not set to an instance of an object.

  - by Lambo

  I have the following code - private static void convert() { string csv = File.ReadAllText("test.csv"); string year = "2008"; XDocument doc = ConvertCsvToXML(csv, new[] { "," }); doc.Save("update.xml"); XmlTextReader reader = new XmlTextReader("update.xml"); XmlDocument testDoc = new XmlDocument(); testDoc.Load(@"update.xml"); XDocument turnip = XDocument.Load("update.xml"); webservice.singleSummary[] test = new webservice.singleSummary[1]; webservice.FinanceFeed CallWebService = new webservice.FinanceFeed(); foreach(XElement el in turnip.Descendants("row")) { test[0].account = el.Descendants("var").Where(x => (string)x.Attribute("name") == "account").SingleOrDefault().Attribute("value").Value; test[0].actual = System.Convert.ToInt32(el.Descendants("var").Where(x => (string)x.Attribute("name") == "actual").SingleOrDefault().Attribute("value").Value); test[0].commitment = System.Convert.ToInt32(el.Descendants("var").Where(x => (string)x.Attribute("name") == "commitment").SingleOrDefault().Attribute("value").Value); test[0].costCentre = el.Descendants("var").Where(x => (string)x.Attribute("name") == "costCentre").SingleOrDefault().Attribute("value").Value; test[0].internalCostCentre = el.Descendants("var").Where(x => (string)x.Attribute("name") == "internalCostCentre").SingleOrDefault().Attribute("value").Value; MessageBox.Show(test[0].account, "Account"); MessageBox.Show(System.Convert.ToString(test[0].actual), "Actual"); MessageBox.Show(System.Convert.ToString(test[0].commitment), "Commitment"); MessageBox.Show(test[0].costCentre, "Cost Centre"); MessageBox.Show(test[0].internalCostCentre, "Internal Cost Centre"); CallWebService.updateFeedStatus(test, year); } It is coming up with the error of - NullReferenceException was unhandled, saying that the object reference not set to an instance of an object. The error occurs on the first line test[0].account. How can I get past this?

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