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  • Set environment variable in Ubuntu

    - by Junho Park
    In Ubuntu, I'd like to switch my JAVA_HOME environment variable back and forth between Java 5 and 6. I open a terminal and type in the following to set the JAVA_HOME environment variable: export JAVA_HOME=/usr/lib/jvm/java-1.5.0-sun And in that same terminal window, I type the following to check that the environment variable has been updated: echo $JAVA_HOME And I see /usr/lib/jvm/java-1.5.0-sun which is what I'm expecting to see. In addition, I modify ~/.profile and set the JAVA_HOME environment variable to /usr/lib/jvm/java-1.5.0-sun. And now for the problem--when I open a new terminal window and I check my JAVA_HOME environment variable by typing in echo $JAVA_HOME I see that my JAVA_HOME environment variable has been reverted back to Java 6. When I reboot my machine (or log out and back in, I suppose) the JAVA_HOME environment variable is set to Java 5 (presumably because of the modification I made in my ~/.profile). Is there a way around this so that I can change my JAVA_HOME environment without having to log out and back in (AND make that environment variable change stick in all new terminal windows)?

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  • call value inside a JS variable as a JS function name

    - by user1640668
    Hello I have a function to perform actions but name of the function is inside a variable... below code will get the URL's hashed part example: #JHON and remove # and store it inside URLHASH variable..example: JHON var urlhash = document.location.hash; urlhash = urlhash.replace(/^.*#/, ''); always there is a function name from that value inside variable and i want to call value inside that variable as a function name window.onload=function() { Value inside URLHASH variable should run as a name of a variable. example: jhon(); }; Is it possible ? I tried some codes but it calls variable name as a function not value inside the variable..help me..

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  • How to improve variable overriding/overwriting in XSL?

    - by ChrisBenyamin
    I want to do the following: Declare a variable Go into a if-statement Overwrite the variable XSL says I can't declare a variable twice, so what can I do to improve this step? Another approach was to check if a variable is set at all. I did this, because i skipped the first step and declared the variable in the if-statement. In another if-statement I wanted to check if the variable exists at all.

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  • get the length/width of value in a factor

    - by Brandon
    How do you get the length of a variable. I am trying to get the last character of factor but the width/length of the contents is variable. I was trying to do something like this: newvariable <- substr(oldvariable, length(oldvariable) -1, length(oldvariable))

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  • How to create a function and pass in variable length argument list?

    - by Jian Lin
    We can create a function p in the following code: var p = function() { }; if (typeof(console) != 'undefined' && console.log) { p = function() { console.log(arguments); }; } but the arguments are passed like an array to console.log, instead of passed one by one as in console.log(arguments[0], arguments[1], arguments[2], ... Is there a way to expand the arguments and pass to console.log like the way above? Note that if the original code were var p = function() { }; if (typeof(console) != 'undefined' && console.log) { p = console.log; } then it works well on Firefox and IE 8 but not on Chrome.

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  • Conflict between variable substitution and CJK characters in BASH

    - by AndreasT
    I encountered a problem with variable substitution in the BASH shell. Say you define a variable a. Then the command $> echo ${a//[0-4]/} prints its value with all the numbers ranged between 0 and 4 removed: $> a="Hello1265-3World" $> echo ${a//[0-4]/} Hello65-World This seems to work just fine, but let's take a look at the next example: $> b="?1265-3?" $> echo ${b//[0-4]/} ?1265-3? Substitution did not take place: I assume that is because b contains CJK characters. This issue extends to all cases in which square brackets are involved. Surprisingly enough, variable substitution without square brackets works fine in both cases: $> a="Hello1265-3World" $> echo ${a//2/} Hello165-3World $> b="?1265-3?" $> echo ${b//2/} ?165-3? Is it a bug or am I missing something? I use Lubuntu 12.04, terminal is lxterminal and echo $BASH_VERSION returns 4.2.24(1)-release. EDIT: Andrew Johnson in his comment stated that with gnome-terminal 4.2.37(1)-release the command works fine. I wonder whether it is a problem of lxterminal or of its specific 4.2.24(1)-release version.

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  • Variable naming conventions?

    - by Ziv
    I've just started using ReSharper (for C#) and I kind of like its code smells finder, it shows me some things about my writing that I meant to fix a long time ago (mainly variable naming conventions). It caused me to reconsider some of my naming conventions for methods and instance variables. ReSharper suggests that instance variable be lower camel case and begin with an underscore. For a while I meant to make all my local variables lower camel case but is the underscore necessary? Do you find it comfortable? I don't like this convention but I also haven't tried it yet, what is you opinion of it? The second thing it prompted me to re-evaluate is my naming conventions for GUI event handlers. I usually use the VS standard of ControlName_Action and my controls usually use hungarian notation (as a suffix, to help clarify in code what is visible to the user and what isn't when dealing with similarly named variable) so I end up with OK_btn_Click(), what is your opinion of that? Should I succumb to the ReSharper convention or there are other equally valid options?

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  • Need help with the naming convention for an incremental variable [closed]

    - by iStryker
    I am using a voting module, that allows you vote either up or down [or reset]. If you vote up, the value is +1. If you vote down, the value is -1. If you vote up then down, the value is -1. I want to extend this module to allow you to vote multiple times, and the votes to be incremental. Examples Up, Up = +1, +1 = +2 Up, Up, Down = +1, +1, -1 = +1 I want to create a new boolean variable. If FALSE/NULL then use the old system +1/-1. If TRUE, voting will be incremental. What should be the name of this variable be? I feel 'incremental' is not the correct name. This module is part of an open-source project and is used on 3,177+ websites, so I want to get the naming convention right. Naturally, I'll be setting an upper and lower limit the variable be. [ie 5 & 0] Side-question: Is there a mathematics term to describe something being either +1/-1?

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  • Python lower_case_with_underscores style convention: underscores not popular?

    - by squirrel
    PEP8 recommends using lowercase, with words separated by underscores as necessary to improve readability for variable and function names. I've seen this interpreted as lower_case_with_underscores by most people, although in practice and in Python's native methods it seems like lowercasewithoutunderscores is more popular. It seems like following PEP8 strictly would be awkward since it seems to suggest mixing both lower_case_with_underscores and lowercasewithoutunderscores, which would be inconsistent. What is your interpretation of PEP8's variable names, and what do you actually use in practice? (Personally, I like lowerCamelCase as a compromise between readability and ease of typing.)

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  • MySQL: Can the table comment length be increased?

    - by Victor Kimura
    I read the MySQL comment length questions on StackOverflow here: http://stackoverflow.com/questions/391323/table-comment-length-in-mysql http://stackoverflow.com/questions/2473934/how-to-increase-mysql-table-comments-length The first link suggests that it can be done and the second suggests it cannot. I don't know why there is this limitation as the comments are very useful. Imagine if there was a limit of 60 characters for your programs. I wrote about this on my site and have some snapshots to the phpMyAdmin and Dbforge MySQL IDEs: http://mysql.tutorialref.com/mysql-table-comment-length-limit.html Is there a way to change this in phpMyAdmin or perhaps even on the CLI? There is a bug commit report from MySQL on this particular problem (follow the first StackOverflow link). It seems to state that the length problem is fixed. I have MySQL 5.1.42. Thank you, Victor

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  • PHP application variable... maybe?

    - by James
    I went to a PHP job interview, I was asked to implement a piece of code to detect visitors are bots to crawl thru the website and steal content. So I implemented a few lines of code to detect if the site is being refreshed/visited too quickly/often by using a session variable to store last visit timestamp. I got told that session varaibles can be manupilated by cookies etc, so I am wondering if there is a application variable that I can use to store the timestamp information against visitor IPs eg $_SERVER[REMOTE_ADDR]? I know that I can write the data to a file but it's not very good for a high traffic website. Regards James

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  • Have loaded a php variable into flash but cant apply it in a function...

    - by Paul Elliot
    hi I have created an actionscript function which stops an animation on a specific frame which works fine. I have then loaded in a php file with a variable which will contain the number for the frame i want the animation to stop on. This has loaded in fine and i have loaded it in a function. what i cant seem to do is to get the variable into the function which tells the animation to stop playing. here is my code: //load variables varReceiver = new LoadVars(); // create an object to store the variables varReceiver.load("http://playground.nsdesign6.net/percentage/external.php"); //load variables //function1 varReceiver.onLoad = function() { //value is the var that is created. var paul = this.percentage; } //function1 //function2 this.onEnterFrame = function() { if(this._currentframe==(percentage)) { this.stop(); this.onEnterFrame = undefined; } } play(); //function2 cheers paul

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  • Sort CMap Key by String Length

    - by Yan Cheng CHEOK
    Previously, I am using STL map to perform the mentioned task. struct ltstr { bool operator()(std::string s1, std::string s2) const { const int l1 = s1.length(); const int l2 = s2.length(); if (l1 == l2) { // In alphabetical order. return s1.compare(s2) < 0; } // From longest length to shortest length. return l1 > l2; } }; std::map<std::string, int, ltstr> m; How can I perform the same task using CMap? // How to make key sorted by string length? CMap<CString, LPCTSTR, int, int> m;

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  • Java - Array's length property

    - by The New Idiot
    We can determine the length of an ArrayList<E> using its public method size() , like ArrayList<Integer> arr = new ArrayList(10); int size = arr.size(); Similarly we can determine the length of an Array object using the length property String[] str = new String[10]; int size = str.length; Whereas the size() method of ArrayList is defined inside the ArrayList class , where is this length property of Array defined ? Is it implemented by JVM or does it reside in any Java API class file ?

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  • In C++, what is the "order of precedence" for shadowed variable names?

    - by Emile Cormier
    In C++, what is the "order of precedence" for shadowed variable names? I can't seem to find a concise answer online. For example: #include <iostream> int shadowed = 1; struct Foo { Foo() : shadowed(2) {} void bar(int shadowed = 3) { std::cout << shadowed << std::endl; // What does this output? } int shadowed; }; int main() { Foo().bar(); } I can't think of any other scopes where a variable might conflict. Please let me know if I missed one.

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  • Is it a good idea to define a variable in a local block for a case of a switch statement?

    - by Paperflyer
    I have a rather long switch-case statement. Some of the cases are really short and trivial. A few are longer and need some variables that are never used anywhere else, like this: switch (action) { case kSimpleAction: // Do something simple break; case kComplexAction: { int specialVariable = 5; // Do something complex with specialVariable } break; } The alternative would be to declare that variable before going into the switch like this: int specialVariable = 5; switch (action) { case kSimpleAction: // Do something simple break; case kComplexAction: // Do something complex with specialVariable break; } This can get rather confusing since it is not clear to which case the variable belongs and it uses some unnecessary memory. However, I have never seen this usage anywhere else. Do you think it is a good idea to declare variables locally in a block for a single case?

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  • Is it bad practice to initialize a variable to a dummy value?

    - by froadie
    This question is a result of the answers to this question that I just asked. It was claimed that this code is "ugly" because it initializes a variable to a value that will never be read: String tempName = null; try{ tempName = buildFileName(); } catch(Exception e){ ... System.exit(1); } FILE_NAME = tempName; Is this indeed bad practice? Should one avoid initializing variables to dummy values that will never actually be used? (EDIT - And what about initializing a String variable to "" before a loop that will concatenate values to the String...? Or is this in a separate category? e.g. String whatever = ""; for(String str : someCollection){ whatever += str; } )

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  • Force an array to recalcuate length after sort

    - by Rhyono
    If you take an array and do the following: arr = []; arr[100] = 1; The length will be 101, which makes sense due to 0-99 being set as undefined Now if we sort that array: arr.sort() it will look like this: [1, undefined x100] since keys are not preserved. However, the length is still 101, since the undefined have all been moved to the end, instead of removed. Is this behavior intentional and if so: is there a built-in function that removes undefined and recalculates and why is it intentional? I am not asking how to write my own function to recalculate length. A sorted array's length can easily be forced with for (x = 0; arr[x] != undefined; x++);arr.length = x;

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  • Error "Input length must be multiple of 8 when decrypting with padded cipher"

    - by Ross Peoples
    I am trying to move a project from C# to Java for a learning exercise. I am still very new to Java, but I have a TripleDES class in C# that encrypts strings and returns a string value of the encrypted byte array. Here is my C# code: using System; using System.IO; using System.Collections.Generic; using System.Security.Cryptography; using System.Text; namespace tDocc.Classes { /// <summary> /// Triple DES encryption class /// </summary> public static class TripleDES { private static byte[] key = { 110, 32, 73, 24, 125, 66, 75, 18, 79, 150, 211, 122, 213, 14, 156, 136, 171, 218, 119, 240, 81, 142, 23, 4 }; private static byte[] iv = { 25, 117, 68, 23, 99, 78, 231, 219 }; /// <summary> /// Encrypt a string to an encrypted byte array /// </summary> /// <param name="plainText">Text to encrypt</param> /// <returns>Encrypted byte array</returns> public static byte[] Encrypt(string plainText) { UTF8Encoding utf8encoder = new UTF8Encoding(); byte[] inputInBytes = utf8encoder.GetBytes(plainText); TripleDESCryptoServiceProvider tdesProvider = new TripleDESCryptoServiceProvider(); ICryptoTransform cryptoTransform = tdesProvider.CreateEncryptor(key, iv); MemoryStream encryptedStream = new MemoryStream(); CryptoStream cryptStream = new CryptoStream(encryptedStream, cryptoTransform, CryptoStreamMode.Write); cryptStream.Write(inputInBytes, 0, inputInBytes.Length); cryptStream.FlushFinalBlock(); encryptedStream.Position = 0; byte[] result = new byte[encryptedStream.Length]; encryptedStream.Read(result, 0, (int)encryptedStream.Length); cryptStream.Close(); return result; } /// <summary> /// Decrypt a byte array to a string /// </summary> /// <param name="inputInBytes">Encrypted byte array</param> /// <returns>Decrypted string</returns> public static string Decrypt(byte[] inputInBytes) { UTF8Encoding utf8encoder = new UTF8Encoding(); TripleDESCryptoServiceProvider tdesProvider = new TripleDESCryptoServiceProvider(); ICryptoTransform cryptoTransform = tdesProvider.CreateDecryptor(key, iv); MemoryStream decryptedStream = new MemoryStream(); CryptoStream cryptStream = new CryptoStream(decryptedStream, cryptoTransform, CryptoStreamMode.Write); cryptStream.Write(inputInBytes, 0, inputInBytes.Length); cryptStream.FlushFinalBlock(); decryptedStream.Position = 0; byte[] result = new byte[decryptedStream.Length]; decryptedStream.Read(result, 0, (int)decryptedStream.Length); cryptStream.Close(); UTF8Encoding myutf = new UTF8Encoding(); return myutf.GetString(result); } /// <summary> /// Decrypt an encrypted string /// </summary> /// <param name="text">Encrypted text</param> /// <returns>Decrypted string</returns> public static string DecryptText(string text) { if (text == "") { return text; } return Decrypt(Convert.FromBase64String(text)); } /// <summary> /// Encrypt a string /// </summary> /// <param name="text">Unencrypted text</param> /// <returns>Encrypted string</returns> public static string EncryptText(string text) { if (text == "") { return text; } return Convert.ToBase64String(Encrypt(text)); } } /// <summary> /// Random number generator /// </summary> public static class RandomGenerator { /// <summary> /// Generate random number /// </summary> /// <param name="length">Number of randomizations</param> /// <returns>Random number</returns> public static int GenerateNumber(int length) { byte[] randomSeq = new byte[length]; new RNGCryptoServiceProvider().GetBytes(randomSeq); int code = Environment.TickCount; foreach (byte b in randomSeq) { code += (int)b; } return code; } } /// <summary> /// Hash generator class /// </summary> public static class Hasher { /// <summary> /// Hash type /// </summary> public enum eHashType { /// <summary> /// MD5 hash. Quick but collisions are more likely. This should not be used for anything important /// </summary> MD5 = 0, /// <summary> /// SHA1 hash. Quick and secure. This is a popular method for hashing passwords /// </summary> SHA1 = 1, /// <summary> /// SHA256 hash. Slower than SHA1, but more secure. Used for encryption keys /// </summary> SHA256 = 2, /// <summary> /// SHA348 hash. Even slower than SHA256, but offers more security /// </summary> SHA348 = 3, /// <summary> /// SHA512 hash. Slowest but most secure. Probably overkill for most applications /// </summary> SHA512 = 4, /// <summary> /// Derrived from MD5, but only returns 12 digits /// </summary> Digit12 = 5 } /// <summary> /// Hashes text using a specific hashing method /// </summary> /// <param name="text">Input text</param> /// <param name="hash">Hash method</param> /// <returns>Hashed text</returns> public static string GetHash(string text, eHashType hash) { if (text == "") { return text; } if (hash == eHashType.MD5) { MD5CryptoServiceProvider hasher = new MD5CryptoServiceProvider(); return ByteToHex(hasher.ComputeHash(Encoding.ASCII.GetBytes(text))); } else if (hash == eHashType.SHA1) { SHA1Managed hasher = new SHA1Managed(); return ByteToHex(hasher.ComputeHash(Encoding.ASCII.GetBytes(text))); } else if (hash == eHashType.SHA256) { SHA256Managed hasher = new SHA256Managed(); return ByteToHex(hasher.ComputeHash(Encoding.ASCII.GetBytes(text))); } else if (hash == eHashType.SHA348) { SHA384Managed hasher = new SHA384Managed(); return ByteToHex(hasher.ComputeHash(Encoding.ASCII.GetBytes(text))); } else if (hash == eHashType.SHA512) { SHA512Managed hasher = new SHA512Managed(); return ByteToHex(hasher.ComputeHash(Encoding.ASCII.GetBytes(text))); } else if (hash == eHashType.Digit12) { MD5CryptoServiceProvider hasher = new MD5CryptoServiceProvider(); string newHash = ByteToHex(hasher.ComputeHash(Encoding.ASCII.GetBytes(text))); return newHash.Substring(0, 12); } return ""; } /// <summary> /// Generates a hash based on a file's contents. Used for detecting changes to a file and testing for duplicate files /// </summary> /// <param name="info">FileInfo object for the file to be hashed</param> /// <param name="hash">Hash method</param> /// <returns>Hash string representing the contents of the file</returns> public static string GetHash(FileInfo info, eHashType hash) { FileStream hashStream = new FileStream(info.FullName, FileMode.Open, FileAccess.Read); string hashString = ""; if (hash == eHashType.MD5) { MD5CryptoServiceProvider hasher = new MD5CryptoServiceProvider(); hashString = ByteToHex(hasher.ComputeHash(hashStream)); } else if (hash == eHashType.SHA1) { SHA1Managed hasher = new SHA1Managed(); hashString = ByteToHex(hasher.ComputeHash(hashStream)); } else if (hash == eHashType.SHA256) { SHA256Managed hasher = new SHA256Managed(); hashString = ByteToHex(hasher.ComputeHash(hashStream)); } else if (hash == eHashType.SHA348) { SHA384Managed hasher = new SHA384Managed(); hashString = ByteToHex(hasher.ComputeHash(hashStream)); } else if (hash == eHashType.SHA512) { SHA512Managed hasher = new SHA512Managed(); hashString = ByteToHex(hasher.ComputeHash(hashStream)); } hashStream.Close(); hashStream.Dispose(); hashStream = null; return hashString; } /// <summary> /// Converts a byte array to a hex string /// </summary> /// <param name="data">Byte array</param> /// <returns>Hex string</returns> public static string ByteToHex(byte[] data) { StringBuilder builder = new StringBuilder(); foreach (byte hashByte in data) { builder.Append(string.Format("{0:X1}", hashByte)); } return builder.ToString(); } /// <summary> /// Converts a hex string to a byte array /// </summary> /// <param name="hexString">Hex string</param> /// <returns>Byte array</returns> public static byte[] HexToByte(string hexString) { byte[] returnBytes = new byte[hexString.Length / 2]; for (int i = 0; i <= returnBytes.Length - 1; i++) { returnBytes[i] = byte.Parse(hexString.Substring(i * 2, 2), System.Globalization.NumberStyles.HexNumber); } return returnBytes; } } } And her is what I've got for Java code so far, but I'm getting the error "Input length must be multiple of 8 when decrypting with padded cipher" when I run the test on this: import java.security.InvalidAlgorithmParameterException; import java.security.InvalidKeyException; import javax.crypto.Cipher; import javax.crypto.NoSuchPaddingException; import javax.crypto.SecretKey; import javax.crypto.spec.IvParameterSpec; import javax.crypto.spec.SecretKeySpec; import com.tdocc.utils.Base64; public class TripleDES { private static byte[] keyBytes = { 110, 32, 73, 24, 125, 66, 75, 18, 79, (byte)150, (byte)211, 122, (byte)213, 14, (byte)156, (byte)136, (byte)171, (byte)218, 119, (byte)240, 81, (byte)142, 23, 4 }; private static byte[] ivBytes = { 25, 117, 68, 23, 99, 78, (byte)231, (byte)219 }; public static String encryptText(String plainText) { try { if (plainText.isEmpty()) return plainText; return Base64.decode(TripleDES.encrypt(plainText)).toString(); } catch (Exception e) { e.printStackTrace(); } return null; } public static byte[] encrypt(String plainText) throws InvalidKeyException, InvalidAlgorithmParameterException, NoSuchPaddingException { try { final SecretKey key = new SecretKeySpec(keyBytes, "DESede"); final IvParameterSpec iv = new IvParameterSpec(ivBytes); final Cipher cipher = Cipher.getInstance("DESede/CBC/PKCS5Padding"); cipher.init(Cipher.ENCRYPT_MODE, key, iv); final byte[] plainTextBytes = plainText.getBytes("utf-8"); final byte[] cipherText = cipher.doFinal(plainTextBytes); return cipherText; } catch (Exception e) { e.printStackTrace(); } return null; } public static String decryptText(String message) { try { if (message.isEmpty()) return message; else return TripleDES.decrypt(message.getBytes()); } catch (Exception e) { e.printStackTrace(); } return null; } public static String decrypt(byte[] message) { try { final SecretKey key = new SecretKeySpec(keyBytes, "DESede"); final IvParameterSpec iv = new IvParameterSpec(ivBytes); final Cipher cipher = Cipher.getInstance("DESede/CBC/PKCS5Padding"); cipher.init(Cipher.DECRYPT_MODE, key, iv); final byte[] plainText = cipher.doFinal(message); return plainText.toString(); } catch (Exception e) { e.printStackTrace(); } return null; } }

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  • String length differs from Javascript to Java code

    - by François P.
    I've got a JSP page with a piece of Javascript validation code which limits to a certain amount of characters on submit. I'm using a <textarea> so I can't simply use a length attribute like in a <input type="text">. I use document.getElementById("text").value.length to get the string length. I'm running Firefox 3.0 on Windows (but I've tested this behavior with IE 6 also). The form gets submitted to a J2EE servlet. In my Java servlet the string length of the parameter is larger than 2000! I've noticed that this can easily be reproduced by adding carriage returns in the <textarea>. I've used Firebug to assert the length of the <textare> and it really is 2000 characters long. On the Java side though, the carriage returns get converted to UNIX style (\r\n, instead of \n), thus the string length differs! Am I missing something obvious here or what ? If not, how would you reliably (cross-platform / browser) make sure that the <textarea> is limited.

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  • java BufferedReader specific length returns NUL characters

    - by Bastien
    I have a TCP socket client receiving messages (data) from a server. messages are of the type length (2 bytes) + data (length bytes), delimited by STX & ETX characters. I'm using a bufferedReader to retrieve the two first bytes, decode the length, then read again from the same bufferedReader the appropriate length and put the result in a char array. most of the time, I have no problem, but SOMETIMES (1 out of thousands of messages received), when attempting to read (length) bytes from the reader, I get only part of it, the rest of my array being filled with "NUL" characters. I imagine it's because the buffer has not yet been filled. char[] bufLen = new char[2]; _bufferedReader.read(bufLen); int len = decodeLength(bufLen); char[] _rawMsg = new char[len]; _bufferedReader.read(_rawMsg); return _rawMsg; I solved the problem in several iterative ways: first I tested the last char of my array: if it wasn't ETX I would read chars from the bufferedReader one by one until I would reach ETX, then start over my regular routine. the consequence is that I would basically DROP one message. then, in order to still retrieve that message, I would find the first occurence of the NUL char in my "truncated" message, read & store additional characters one at a time until I reached ETX, and append them to my "truncated" messages, confirming length is ok. it works also, but I'm really thinking there's something I could do better, like checking if the total number of characters I need are available in the buffer before reading it, but can't find the right way to do it... any idea / pointer ? thanks !

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  • How to understand "if ( obj.length === +obj.length )" Javascript condition statement?

    - by humanityANDpeace
    I have run across a condition statement which I have some difficulties to understand. It looks like (please note the +-sign on the right-hand-side) this: obj.length === +obj.length. Can this condition and its purpose/syntax be explained? Looking at the statement (without knowing it) provokes the impression that it is a dirty hack of some sort, but I am almost certain that underscore.js is rather a well designed library, so there must be a better explanation. Background I found this statement used in some functions of the underscore.js library (underscore.js annotated source). My guesswork is that this condition statement is somehow related to testing for a variable obj to be of Array type? (but I am totally unsure). I have tried to test this using this code. var myArray = [1,2,3]; testResult1 = myArray.length === +myArray.length; console.log( testResult1 ); //prints true var myObject = { foo : "somestring", bar : 123 }; testResult2 = myObject.length === +myObject.length; console.log( testResult2 ); //prints false

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  • Who knows the value of global variables in the qt qtscript script to access the global variable to change the global variable value; [closed]

    - by dawntrees
    Who knows the value of global variables in the qt qtscript script to access the global variable to change the global variable value; forexample int gVar=0; int main(int argc, char *argv[]) { QScriptEngine engine; QScriptValue varValue = m_engine-newVariant(gVar); engine.globalObject().setProperty("gVar", varValue); QScriptValue result = m_engine->evaluate("gVar=100;"); qDebug()<<"gVar================"<<gVar; return 0; } Why gVar = 0 and not equal to 100; how can we make gVar equal to 100(gVar=100) Who can help group I appreciate it, thanks!

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  • Inherit one instance variable from the global scope

    - by Julian
    I'm using Curses to create a command line GUI with Ruby. Everything's going well, but I have hit a slight snag. I don't think Curses knowledge (esoteric to be fair) is required to answer this question, just Ruby concepts such as objects and inheritance. I'm going to explain my problem now, but if I'm banging on, just look at the example below. Basically, every Window instance needs to have .close called on it in order to close it. Some Window instances have other Windows associated with it. When closing a Window instance, I want to be able to close all of the other Window instances associated with it at the same time. Because associated Windows are generated in a logical fashion, (I append the name with a number: instance_variable_set(self + integer, Window.new(10,10,10,10)) ), it's easy to target generated windows, because methods can anticipate what assosiated windows will be called, (I can recreate the instance variable name from scratch, and almost query it: instance_variable_get(self + integer). I have a delete method that handles this. If the delete method is just a normal, global method (called like this: delete_window(@win543) then everything works perfectly. However, if the delete method is an instance method, which it needs to be in-order to use the self keyword, it doesn't work for a very clear reason; it can 'query' the correct instance variable perfectly well (instance_variable_get(self + integer)), however, because it's an instance method, the global instances aren't scoped to it! Now, one way around this would obviously be to simply make a global method like this: delete_window(@win543). But I have attributes associated with my window instances, and it all works very elegantly. This is very simplified, but it literally translates the problem exactly: class Dog def speak woof end end def woof if @dog_generic == nil puts "@dog_generic isn't scoped when .woof is called from a class method!\n" else puts "@dog_generic is scoped when .woof is called from the global scope. See:\n" + @dog_generic end end @dog_generic = "Woof!" lassie = Dog.new lassie.speak #=> @dog_generic isn't scoped when .woof is called from an instance method!\n woof #=> @dog_generic is scoped when .woof is called from the global scope. See:\nWoof! TL/DR: I need lassie.speak to return this string: "@dog_generic is scoped when .woof is called from the global scope. See:\nWoof!" @dog_generic must remain as an insance variable. The use of Globals or Constants is not acceptable. Could woof inherit from the Global scope? Maybe some sort of keyword: def woof < global # This 'code' is just to conceptualise what I want to do, don't take offence! end Is there some way the .woof method could 'pull in' @dog_generic from the global scope? Will @dog_generic have to be passed in as a parameter?

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