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• Deterministic and non uniform long string generation from seed

  - by Limonup

  I had this weird idea for an encryption that I wanted to try out, it may be bad, and it may have done before, but I'm just doing it for fun. The short version of the question is: Is it possible to generate a long, deterministic and non-uniformly distributed string/sequence of numbers from a small seed? Long(er) version: I was thinking to encrypt a text by changing encoding. The new encoding would be generated via Huffman algorithm. To work well, the Huffman algorithm would need a fairly long text with non uniform distribution. Then characters can have different bit-lengths which would be the primary strength of this encryption. The problem is that its impractical to enter in/remember a long text each time you want to decrypt the text. So I was wondering if it was possible to generate a text from password seed? It doesn't matter what the text is, as long as it has non uniform distribution of characters and that the exact same sequence can be recreated each time you give it the same seed. Preferably, are there any functions/extensions in Python that can do this? EDIT: To expand on the "strength" of varying bit length: if I have a string "test", ASCII values 116, 101, 115, 116, which gives bit values of 1110100 1100101 1110011 1110100 Then, say my Huffman algorithm generates encoding like t = 101 e = 1100111 s = 10001 The final string is 101 1100111 10001 101, if we encode this back to ASCII, we get 1011100 1111000 1101000, which is 3 entirely different characters. Obviously its impossible to perform any kind of frequency analysis or something like that on this.

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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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• C/C++ Control Structure Limitations?

  - by STingRaySC

  I have heard of a limitation in VC++ (not sure which version) on the number of nested if statements (somewhere in the ballpark of 300). The code was of the form: if (a) ... else if (b) ... else if (c) ... ... I was surprised to find out there is a limit to this sort of thing, and that the limit is so small. I'm not looking for comments about coding practice and why to avoid this sort of thing altogether. Here's a list of things that I'd imagine could have some limitation: Number of functions in a scope (global, class, or namespace). Number of expressions in a single statement (e.g., compound conditionals). Number of cases in a switch. Number of parameters to a function. Number of classes in a single hierarchy (either inheritance or containment). What other control structures/language features have limits such as this? Do the language standards say anything about these limits (perhaps minimum requirements for an implementation)? Has anyone run into a particular language limitation like this with a particular compiler/implementation? EDIT: Please note that the above form of if statements is indeed "nested." It is equivalent to: if (a) { //... } else { if (b) { //... } else { if (c) { //... } else { //... } } }

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• Fastcgi 500 error on preg_match_all in PHP

  - by Bertvan

  Hi, I'm trying to set up some exotic PHP code (I'm no expert), and I get a FastCGI Error 500 on a PHP line containing 'preg_match_all'. When I comment out the line, the page is returned with a 200 (but not how it was meant to be). The code is parsing php, html and javascript content loaded from the database and is composing them to return the finished page. Now, by placing around some error_log entries I could determine that the line with the preg_match_all is the cause of the 500. However the line is hit multiple times during the loading of the page and on other occasions, the line does not cause an error. Here's how it looks like exactly: preg_match_all ("/(<([\w]+)[^>]*>)((?:.|\n)*)(<\/\\2>)/", $part['data'], $tags, PREG_PATTERN_ORDER|PREG_OFFSET_CAPTURE); The subject string is a piece of text that looks like: <script> ... some javascript functions ... </script> [Edit:] This is code that is up and running correctly elsewhere, so this very well could be a PHP setting or environment difference. I'm using PHP 5.2.13 on IIS6 with FastCGI. [Edit:] Nothing is mentioned in the log files. At least not in the ones I checked: IIS Logs Event Logs PHP Log Any thoughts or direction would be welcome.

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• SQL Distinct keyword in assignment statement

  - by Brandi

  I have a query that works: DECLARE @ProductID int SET @ProductID = '1234' SELECT DISTINCT TOP 12 a.ProductID FROM A a WHERE a.CategoryID IN (SELECT b.CategoryID FROM B b WHERE b.ProductID = @ProductID) AND a.ProductID != @ProductID It returns a list of 12 product numbers, all unique. I need to store these results in a variable, comma separated, because that's what 3rd party stored procedure needs. So I have this: DECLARE @ProductID int DECLARE @relatedprods varchar(8000) SET @ProductID = '1234' SET @relatedprods = '' SELECT TOP 12 @relatedprods = @relatedprods + CONVERT(VARCHAR(20), a.ProductID) + ', ' FROM A a WHERE a.CategoryID IN (SELECT b.CategoryID FROM B b WHERE B.ProductID = @ProductID) AND a.ProductID != @ProductID SELECT @relatedprods Now, none of these are distinct, but it is returning 12 rows. Now I add the 'distinct' back in, like in the first query: DECLARE @ProductID int DECLARE @relatedprods varchar(8000) SET @ProductID = '1234' SET @relatedprods = '' SELECT DISTINCT TOP 12 @relatedprods = @relatedprods + CONVERT(VARCHAR(20), a.ProductID) + ', ' FROM A a WHERE a.CategoryID IN (SELECT b.CategoryID FROM B b WHERE B.ProductID = @ProductID) AND a.ProductID != @ProductID SELECT @relatedprods Only one product is returned in the comma separated list! Does 'distinct' not work in assignment statements? What did I do wrong? Or is there a way to get around this? Thanks in advance!

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• C# class design - expose variables for reading but not setting

  - by James Brauman

  I have a a polygon class which stores a list of Microsoft.Xna.Framework.Vector2 as the vertices of the polygon. Once the polygon is created, I'd like other classes to be able to read the position of the vertices, but not change them. I am currently exposing the vertices through this field: /// <summary> /// Gets the vertices stored for this polygon. /// </summary> public List<Vector2> Vertices { get { return _vertices; } } List<Vector2> _vertices; However you can change any vertex using code like: Polygon1.Vertices[0] = new Vector2(0, 0); or Polygon1.Vertices[0].X = 0; How can I limit other classes to be able to only read the properties of these vertices, and not be able to set a new one to my List? The only thing I can think of is to pass a copy to classes that request it. Note that Vector2 is a struct that is part of the XNA framework and I cannot change it. Thanks.

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• TSQL - make a literal float value

  - by David B

  I understand the host of issues in comparing floats, and lament their use in this case - but I'm not the table author and have only a small hurdle to climb... Someone has decided to use floats as you'd expect GUIDs to be used. I need to retrieve all the records with a specific float value. sp_help MyTable -- Column_name Type Computed Length Prec -- RandomGrouping float no 8 53 Here's my naive attempt: --yields no results SELECT RandomGrouping FROM MyTable WHERE RandomGrouping = 0.867153569942739 And here's an approximately working attempt: --yields 2 records SELECT RandomGrouping FROM MyTable WHERE RandomGrouping BETWEEN 0.867153569942739 - 0.00000001 AND 0.867153569942739 + 0.00000001 -- 0.867153569942739 -- 0.867153569942739 In my naive attempt, is that literal a floating point literal? Or is it really a decimal literal that gets converted later? If my literal is not a floating point literal, what is the syntax for making a floating point literal? EDIT: Another possibility has occurred to me... it may be that a more precise number than is displayed is stored in this column. It may be impossible to create a literal that represents this number. I will accept answers that demonstrate that this is the case. EDIT: response to DVK. TSQL is MSSQLServer's dialect of SQL. This script works, and so equality can be performed deterministically between float types: DECLARE @X float SELECT top 1 @X = RandomGrouping FROM MyTable WHERE RandomGrouping BETWEEN 0.839110948199148 - 0.000000000001 AND 0.839110948199148 + 0.000000000001 --yields two records SELECT * FROM MyTable WHERE RandomGrouping = @X I said "approximately" because that method tests for a range. With that method I could get values that are not equal to my intended value. The linked article doesn't apply because I'm not (intentionally) trying to straddle the world boundaries between decimal and float. I'm trying to work with only floats. This isn't about the non-convertibility of decimals to floats.

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• Which of these is better practice?

  - by Fletcher Moore

  You have a sequence of functions to execute. Case A: They do not depend on each other. Which of these is better? function main() { a(); b(); c(); } or function main() { a(); } function a() { ... b(); } function b() { ... c(); } Case B: They do depend on successful completion of the previous. function main() { if (a()) if (b()) c(); } or function main() { if (!a()) return false; if (!b()) return false; c(); } or function main() { a(); } function a() { ... // maybe return false b(); } funtion b() { ... // maybe return false c(); } Better, of course, means more maintainable and easier to follow.

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• comparing salt and hashed passwords during login doesn't seem work right....

  - by Pandiya Chendur

  I stored salt and hash values of password during user registration... But during their login i then salt and hash the password given by the user, what happens is a new salt and a new hash is generated.... string password = collection["Password"]; reg.PasswordSalt = CreateSalt(6); reg.PasswordHash = CreatePasswordHash(password, reg.PasswordSalt); These statements are in both registration and login.... salt and hash during registration was eVSJE84W and 18DE22FED8C378DB7716B0E4B6C0BA54167315A2 During login it was 4YDIeARH and 12E3C1F4F4CFE04EA973D7C65A09A78E2D80AAC7..... Any suggestion.... public static string CreateSalt(int size) { //Generate a cryptographic random number. RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider(); byte[] buff = new byte[size]; rng.GetBytes(buff); // Return a Base64 string representation of the random number. return Convert.ToBase64String(buff); } public static string CreatePasswordHash(string pwd, string salt) { string saltAndPwd = String.Concat(pwd, salt); string hashedPwd = FormsAuthentication.HashPasswordForStoringInConfigFile( saltAndPwd, "sha1"); return hashedPwd; }

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• Is there a way to toggle bluetooth and/or wifi on and off programatically in iOS?

  - by Andy W

  I am looking for an easy way to toggle both bluetooth and wifi between on and off states on iOS 4.x devices (iPhone and iPad). I am constantly toggling these functions as I move between different locations and usage scenarios, and right now it takes multiple taps and visits to the Settings App. I am looking to create a simple App, that lives on Springboard, that I can just tap and it will turn off the wifi if it's on, and vice versa, then immediately quit. Similarly with an App for toggling bluetooth’s state. I have the developer SDK, and am comfortable in Xcode and with iOS development, so am happy to write the required Xcode to create the App. I am just at a loss as to which API, private or not, has the required functionality to simply toggle the state of these facilities. Because this is scratching a very personal itch, I have no intent to try and sell the App or get it up on the App store, so conforming with App guidelines on API usage is a non-issue. What I don’t want to do is jailbreak the devices, as I want to keep the core software as shipped. Can anyone point me at some sample code or more info on achieving this goal, as my Google-fu is letting me down, and if the information is out there for 4.x devices I just can’t find it.

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• Trying to write up a C daemon, but don't know enough C to continue

  - by JamesM-SiteGen

  Okay, so I want this daemon to run in the background with little to no interaction. I plan to have it work with Apache, lighttpd, etc to send the session & request information to allow C to generate a website from an object DB, saving will have to be an option so, you can start the daemon with an existing DB but will not save to it unless you login to the admin area and enable, and restart the daemon. Summary of the daemon: Load a database from file. Have a function to restart the daemon. Allow Apache, lighttpd, etc to get necessary data about the request and session. A varible to allow the database to be saved to the file, otherwise it will only be stored in ram. If it is set to save back to the file, then only have neccessary data in ram. Use sql-light for the database file. Build a webpage from some template files. $(myVar) for getting variables. Get templates from a directory. ./templates/01-test/{index.html,template.css,template.js} Live version of the code and more information: http://typewith.me/YbGB1h1g1p Also I am working on a website CMS in php, but I am tring to switch to C as it is faster than php. ( php is quite fast, but the fact that making a few mySQL requests for every webpage is quite unefficent and I'm sure that it can be far better, so an object that we can recall data from in C would have to be faster ) P.S I am using Arch-Linux not MS-Windows, with the package group base-devel for the common developer tools such as make and makepgk. Edit: Oupps, forgot the question ;) Okay, so the question is, how can I turn this basic C daemon into a base to what I am attempting to do here?

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• highlight the text of the DOM range element,

  - by ganapati hegde

  I select some text on the html page(opened in firefox) using mouse,and using javascript functions, i create/get the rangeobject corresponding to the selected text. userSelection =window.getSelection(); var rangeObject = getRangeObject(userSelection); Now i want to highlight all the text which comes under the rangeobject.I am doing it like this, var span = document.createElement("span"); rangeObject.surroundContents(span); span.style.backgroundColor = "yellow"; Well,this works fine, only when the rangeobject(startpoint and endpoint) lies in the same textnode,then it highlights the corresponding text.Ex <p>In this case,the text selected will be highlighted properly, because the selected text lies under a single textnode</p> But if the rangeobject covers more than one textnode, then it is not working properlay, It highlights only the texts which lie in the first textnode,Ex <p><h3>In this case</h3>, only the text inside the header(h3) will be highlighted, not any text outside the header</p> Any idea how can i make, all the texts which comes under rangeobject,highlighted,independent of whether range lies in a single node or multiple node? Thanks....

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• Choose a XML node in SQL Server based on max value of a child element

  - by Jay

  I am trying to select from SQL Server 2005 XML datatype some values based on the max data that is located in a child node. I have multiple rows with XML similar to the following stored in a field in SQL Server: <user> <name>Joe</name> <token> <id>ABC123</id> <endDate>2013-06-16 18:48:50.111</endDate> </token> <token> <id>XYX456</id> <endDate>2014-01-01 18:48:50.111</endDate> </token> </user> I want to perform a select from this XML column where it determines the max date within the token element and would return the datarows similar to the result below for each record: Joe XYZ456 2014-01-01 18:48:50.111 I have tried to find a max function for xpath that would all me to select the correct token element but I couldn't find one that would work. I also tried to use the SQL MAX function but I wasn't able to get it working with that method either. If I only have a single token it of course works fine but when I have more than one I get a NULL, most likely because the query doesn't know which date to pull. I was hoping there would be a way to specify a where clause [max(endDate)] on the token element but haven't found a way to do that. Here is an example of the one that works when I only have a single token: SELECT XMLCOL.query('user/name').value('.','NVARCHAR(20)') as name XMLCOL.query('user/token/id').value('.','NVARCHAR(20)') as id XMLCOL.query('user/token/endDate').value(,'xs:datetime(.)','DATETIME') as endDate FROM MYTABLE

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• Calculate posterior distribution of unknown mis-classification with PRTools in MATLAB

  - by Samuel Lampa

  I'm using the PRTools MATLAB library to train some classifiers, generating test data and testing the classifiers. I have the following details: N: Total # of test examples k: # of mis-classification for each classifier and class I want to do: Calculate and plot Bayesian posterior distributions of the unknown probabilities of mis-classification (denoted q), that is, as probability density functions over q itself (so, P(q) will be plotted over q, from 0 to 1). I have that (math formulae, not matlab code!): P(q|k,N) = Posterior * Prior / Normalization constant = P(k|q,N) * P(q|N) / P(k|N) The prior is set to 1, so I only need to calculate the posterior and normalization constant. I know that the posterior can be expressed as (where B(N,k) is the binomial coefficient): P(k|q,N) = B(N,k) * q^k * (1-q)^(N-k) ... so the Normalization constant is simply an integral of the posterior above, from 0 to 1: P(k|N) = B(N,k) * integralFromZeroToOne( q^k * (1-q)^(N-k) ) (The Binomial coefficient ( B(N,k) ) can be omitted thoughappears in both the posterior and normalization constant, so it can be omitted.) Now, I've heard that the integral for the normalization constant should be able to be calculated as a series ... something like: k!(N-k)! / (N+1)! Is that correct? (I have some lecture notes from with this series, but can't figure out if it is for the normalization constant integral, or for the posterior distribution of mis-classification (q)) Also, hints are welcome as how to practically calculate this? (factorials are easily creating truncation errors right?) ... AND, how to practically calculate the final plot (the posterior distribution over q, from 0 to 1).

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• Searching a column containing CSV data in a MySQL table for existence of input values

  - by Adarsh R

  Hi, I have a table say, ITEM, in MySQL that stores data as follows: ID FEATURES -------------------- 1 AB,CD,EF,XY 2 PQ,AC,A3,B3 3 AB,CDE 4 AB1,BC3 -------------------- As an input, I will get a CSV string, something like "AB,PQ". I want to get the records that contain AB or PQ. I realized that we've to write a MySQL function to achieve this. So, if we have this magical function MATCH_ANY defined in MySQL that does this, I would then simply execute an SQL as follows: select * from ITEM where MATCH_ANY(FEAURES, "AB,PQ") = 0 The above query would return the records 1, 2 and 3. But I'm running into all sorts of problems while implementing this function as I realized that MySQL doesn't support arrays and there's no simple way to split strings based on a delimiter. Remodeling the table is the last option for me as it involves lot of issues. I might also want to execute queries containing multiple MATCH_ANY functions such as: select * from ITEM where MATCH_ANY(FEATURES, "AB,PQ") = 0 and MATCH_ANY(FEATURES, "CDE") In the above case, we would get an intersection of records (1, 2, 3) and (3) which would be just 3. Any help is deeply appreciated. Thanks

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• Risking the exception anti-pattern.. with some modifications

  - by Sridhar Iyer

  Lets say that I have a library which runs 24x7 on certain machines. Even if the code is rock solid, a hardware fault can sooner or later trigger an exception. I would like to have some sort of failsafe in position for events like this. One approach would be to write wrapper functions that encapsulate each api a: returnCode=DEFAULT; try { returnCode=libraryAPI1(); } catch(...) { returnCode=BAD; } return returnCode; The caller of the library then restarts the whole thread, reinitializes the module if the returnCode is bad. Things CAN go horribly wrong. E.g. if the try block(or libraryAPI1()) had: func1(); char *x=malloc(1000); func2(); if func2() throws an exception, x will never be freed. On a similar vein, file corruption is a possible outcome. Could you please tell me what other things can possibly go wrong in this scenario?

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• String operations

  - by NEO

  I am trying to find the most repeated word in a string. My code is as follows: public class Word { private String toWord; private int Count; public Word(int count, String word){ toWord = word; Count = count; } public static void main(String args[]){ String str="my name is neo and my other name is also neo because I am neo"; String []str1=str.split(" "); Word w1=new Word(0,str1[0]); LinkedList<Word> list = new LinkedList<Word>(); list.add(w1); ListIterator itr = list.listIterator(); for(int i=1;i<str1.length;i++){ while(itr.hasNext()){ if(str1[i].equalsTO(????)); else list.add(new Word(0,str1[i])); } How do I compare the string from string array str1 to the string stored in the linked list and then how do i increase the respective count. I will then print the string with the highest count, I dont know how to do that either.

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• MySQL: Get average of time differences?

  - by Nebs

  I have a table called Sessions with two datetime columns: start and end. For each day (YYYY-MM-DD) there can be many different start and end times (HH:ii:ss). I need to find a daily average of all the differences between these start and end times. An example of a few rows would be: start: 2010-04-10 12:30:00 end: 2010-04-10 12:30:50 start: 2010-04-10 13:20:00 end: 2010-04-10 13:21:00 start: 2010-04-10 14:10:00 end: 2010-04-10 14:15:00 start: 2010-04-10 15:45:00 end: 2010-04-10 15:45:05 start: 2010-05-10 09:12:00 end: 2010-05-10 09:13:12 ... The time differences (in seconds) for 2010-04-10 would be: 50 60 300 5 The average for 2010-04-10 would be 103.75 seconds. I would like my query to return something like: day: 2010-04-10 ave: 103.75 day: 2010-05-10 ave: 72 ... I can get the time difference grouped by start date but I'm not sure how to get the average. I tried using the AVG function but I think it only works directly on column values (rather than the result of another aggregate function). This is what I have: SELECT TIME_TO_SEC(TIMEDIFF(end,start)) AS timediff FROM Sessions GROUP BY DATE(start) Is there a way to get the average of timediff for each start date group? I'm new to aggregate functions so maybe I'm misunderstanding something. If you know of an alternate solution please share. I could always do it ad hoc and compute the average manually in PHP but I'm wondering if there's a way to do it in MySQL so I can avoid running a bunch of loops. Thanks.

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• How to open the download window when a dynamically created link is clicked in asp.net

  - by Ranjana

  i have stored the txtfile in the database.i need to show the txtfile when i clik the link. and this link has to be created dynamically. my code below: aspx code: aspx.cs protected void Page_Load(object sender, EventArgs e) { if(!Page.IsPostBack) { DataTable dtassignment = new DataTable(); dtassignment = serviceobj.DisplayAssignment(Session["staffname"].ToString()); if (dtassignment != null) { Byte[] bytes = (Byte[])dtassignment.Rows[0]["Data"]; //download(dtassignment); } divlink.InnerHtml = ""; divlink.Visible = true; foreach (DataRow r in dtassignment.Rows) { divlink.InnerHtml += "<a href='" + "'onclick='download(dtassignment)'>" + r["Filename"].ToString() + "</a>" + "<br/>"; } } } - public void download(DataTable dtassignment) { System.Diagnostics.Debugger.Break(); Byte[] bytes = (Byte[])dtassignment.Rows[0]["Data"]; Response.Buffer = true; Response.Charset = ""; Response.Cache.SetCacheability(HttpCacheability.NoCache); Response.ContentType = dtassignment.Rows[0]["ContentType"].ToString(); Response.AddHeader("content-disposition", "attachment;filename=" + dtassignment.Rows[0]["FileName"].ToString()); Response.BinaryWrite(bytes); Response.Flush(); Response.End(); } i have got the link dynamically, but i did not able to download the txtfile when i clik the link. how to carry out this. pls help me out...

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• Paste or Drop, copy data and release source?

  - by Harvey

  I have an MFC DocView SDI App that receives data from either the clipboard or drag and drop. The data is in either CF_HDROP or CF_TEXT format. I have a COleDropTarget derived CMyDropTarget member m_dropTarget of my CMainFrame class. I have two member functions of CMyDropTarget; OnDrop(...) and OnPaste() which each call another member function PostData(pDataObject). I want to get a copy of the pDataObject from either CF_... format and PostMessage to my CmainFrame which will call a member of my Doc class. What is a simple way of getting a copy of the global data to pass with the PostMessage() so that I can get the drop source released before I get around to processing the global data? NOTE that they are always treated as a copy of the source data, so there is no need for the source to delete anything when the operation is done. Or perhaps a better way of asking the question is: How can I release the Drop source before processing the global data? Can I pass the HGLOBAL via PostMessage and still release the source without making a copy of it?

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• How to get MySQL database to appear on index.php

  - by Teddy Truong

  Hi, I have a submission form on my website (index.php) and I have the data(user submissions) being stored into a MySQL database. Right now, I have the user submitting a post and then the page directs them to an update.php which shows what they inputed. However, I want all of the data in the database in MySQL to be shown on the index.php. It's a lot like a comment system. User submits a post... and sees their post above the other submitted posts all on the same page. I think I'm missing AJAX... ? Here is the code for index.php <div align="center"> <p>&nbsp;</p> <h2 align="center" class="Title"><em><strong>REDACTED</strong></em></h2> <form id="form1" name="form1" method="post" action="update.php"> <hr /> <label><br /> <form action="update.php" method="post"> REDACTED: <input type="text" name="text" /> <input type="submit" /> </form> </label> </form> </div> On update.php I have this: ?php $text = $_POST['text']; $myString = "REDACTED"; mysql_connect ("db----.net", "-----3", "------------") or die ('Error: ' . mysql_error()); mysql_select_db ("-----------"); $query="INSERT INTO TextArea (ID, text) VALUES ('NULL', '".$text."')"; mysql_query($query) or die ('Error updating database'); echo " $myString "," $text "; ?> Thanks a lot!

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• How does the socket API accept() function work?

  - by Eli Bendersky

  The socket API is the de-facto standard for TCP/IP and UDP/IP communications (that is, networking code as we know it). However, one of its core functions, accept() is a bit magical. To borrow a semi-formal definition: accept() is used on the server side. It accepts a received incoming attempt to create a new TCP connection from the remote client, and creates a new socket associated with the socket address pair of this connection. In other words, accept returns a new socket through which the server can communicate with the newly connected client. The old socket (on which accept was called) stays open, on the same port, listening for new connections. How does accept work? How is it implemented? There's a lot of confusion on this topic. Many people claim accept opens a new port and you communicate with the client through it. But this obviously isn't true, as no new port is opened. You actually can communicate through the same port with different clients, but how? When several threads call recv on the same port, how does the data know where to go? I guess it's something along the lines of the client's address being associated with a socket descriptor, and whenever data comes through recv it's routed to the correct socket, but I'm not sure. It'd be great to get a thorough explanation of the inner-workings of this mechanism.

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• What are the responsibilities of the data layer?

  - by alimac83

  I'm working on a project where I had to add a data layer to my application. I've always thought that the data layer is purely responsible for CRUD functions ie. shouldn't really contain any logic but should simply retrieve data for the business layer to manipulate. However I'm a little confused with my project because I'm not sure whether I've structured my app correctly for this scenario. Basically I'm trying to retrieve a list of products from the database that fall within a certain pricing threshold. At the moment I have a function in my data layer that basically returns all products where price min threshold and price < max threshold. But it got me thinking that maybe this is incorrect. Should the data layer simply return a list of ALL products and then the business logic do the filtering? I'm pretty confused over whether the data layer should simply provide methods that allow the business layer to get raw data or whether it should be responsible for getting filtered data too? If anyone has an article or something explaining this in detail it'd be very helpful. Thanks

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• How can I alter an external variable from inside my AJAX?

  - by tmedge

  I keep on having these same two problems. I have been trying to use Remy Sharp's wonderful tagSuggest plugin, and it works great. Until I try to use an AJAX call to get tags from my database. My setGlobalTags() works great, with my defined myTagList at the top of the function. What I want to do is set myTagList equal to the result from my AJAX. My problem is that I can neither call setGlobalTags() from inside my success or error functions, nor actually alter the original myTagList. Also, I keep on having this other issue as well. I keep this code in my Master page, and my AJAX returns 'success' on almost every page. I only (and always) get the error alert when I navigate to a page that actually contains something of id="ParentTags". I don't see why this is happening, because my $('#ParentTags').tagSuggest(); is definitely after my AJAX call. I realize that this is probably just some dumb conventions error, but I am new to this and I'm here to learn from you guys. Thanks in advance! $(function() { var myTagList = ['test', 'testMore', 'testALot']; $.ajax({ type: "POST", url: 'Admin/GetTagList', dataType: 'json', success: function(resultTags) { myTagList = resultTags; alert(myTagList[0]); setGlobalTags(myTagList); }, error: function() { alert('Error'); setGlobalTags(myTagList); } }); setGlobalTags(myTagList); $('#ParentTags').tagSuggest(); });

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• FindWindowEx from user32.dll is returning a handle of Zero and error code of 127 using dllimport

  - by puretechy

  I need to handle another windows application programatically, searching google I found a sample which handles windows calculator using DLLImport Attribute and importing the user32.dll functions into managed ones in C#. The application is running, I am getting the handle for the main window i.e. Calculator itself, but the afterwards code is not working. The FindWindowEx method is not returning the handles of the children of the Calculator like buttons and textbox. I have tried using the SetLastError=True on DLLImport and found that I am getting an error code of 127 which is "Procedure not found". This is the link from where I got sample application: http://www.codeproject.com/script/Articles/ArticleVersion.aspx?aid=14519&av=34503 Please help if anyone knows how to solve it. UPDATE: The DLLImport is: [DllImport("user32.dll", SetLastError = true)] public static extern IntPtr FindWindowEx(IntPtr parentHandle, IntPtr childAfter, string className, string windowTitle); The Code that is not working is: hwnd=FindWindow(null,"Calculator"); // This is working, I am getting handle of Calculator // The following is not working, I am getting hwndChild=0 and err = 127 hwndChild = FindWindowEx((IntPtr)hwnd,IntPtr.Zero,"Button","1"); Int32 err = Marshal.GetLastWin32Error();

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