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  • What is the meaning of method class in the class definition in Ruby?

    - by Steven Xu
    I'm familiar with function definitions and variable declarations being in class definitions: public class MyClass { public int myvar; public void doSomething() { } } But what does it "mean" in Ruby when a method is actually called in the class definition? This happens amply in Rails, for instance: class User < ActiveRecord::Base has_many :posts end What exactly does this do (at a lower level than "it adds some methods to the class")? How would I implement such a function (e.g., one that mixes in some additional methods)?

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  • Type-inferring a constant in C#

    - by Andreas Grech
    In C#, the following type-inference works: var s = "abcd"; But why can't the type be inferred when the variable is a constant? The following throws a compile-time exception: const var s = "abcd"; // <= Compile time error: // Implicitly-typed local variables cannot be constant

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  • Generate syntax tree for simple math operations

    - by M28
    I am trying to generate a syntax tree, for a given string with simple math operators (+, -, *, /, and parenthesis). Given the string "1 + 2 * 3": It should return an array like this: ["+", [1, ["*", [2,3] ] ] ] I made a function to transform "1 + 2 * 3" in [1,"+",2,"*",3]. The problem is: I have no idea to give priority to certain operations. My code is: function isNumber(ch){ switch (ch) { case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9': case '.': return true; break; default: return false; break; } } function generateSyntaxTree(text){ if (typeof text != 'string') return []; var code = text.replace(new RegExp("[ \t\r\n\v\f]", "gm"), ""); var codeArray = []; var syntaxTree = []; // Put it in its on scope (function(){ var lastPos = 0; var wasNum = false; for (var i = 0; i < code.length; i++) { var cChar = code[i]; if (isNumber(cChar)) { if (!wasNum) { if (i != 0) { codeArray.push(code.slice(lastPos, i)); } lastPos = i; wasNum = true; } } else { if (wasNum) { var n = Number(code.slice(lastPos, i)); if (isNaN(n)) { throw new Error("Invalid Number"); return []; } else { codeArray.push(n); } wasNum = false; lastPos = i; } } } if (wasNum) { var n = Number(code.slice(lastPos, code.length)); if (isNaN(n)) { throw new Error("Invalid Number"); return []; } else { codeArray.push(n); } } })(); // At this moment, codeArray = [1,"+",2,"*",3] return syntaxTree; } alert('Returned: ' + generateSyntaxTree("1 + 2 * 3"));

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  • How to maintain precision using DateTime.Now.Ticks in C#

    - by nmr
    I know that when I use DateTime.Now.Ticks in C# it returns a long value but I need to store it in an int variable and I am confused as to whether or not I can maintain that precision. As of right now I just have a cast int timeStampValue = (int)DateTime.Now.Ticks; Any suggestions or advice on how to maintain the precision, if possible, would be much appreciated.

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  • Android: View.getTag/setTag and IllegalArgumentException

    - by Sparafusile
    Yes, I know you need a unique resource id when calling the version of these functions that requires a key, but I cannot for the life of me figure out how to create a resource id that can be used in this way. A final variable in my class wont work and neither will a hard coded value. Both threw an IllegalArgumentException. So what gives, how do you use these methods? Spara

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  • Managing a user's PHP session with Cocoa Touch

    - by Calvin L
    I'm building an iPhone app, which will allow users to log in to a PHP web server that authenticates the user and starts a session. My idea for managing a session is to create a singleton User class that has a sharedLogin method. Would it be prudent to store the session variable in the shared instance in order to maintain the session?

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  • Byte to Integer in c#

    - by jtb
    I am reading a row from a SQL Server table. One of the columns is of type tinyint. I want to get the value into an int or int32 variable. rdr.GetByte(j) (byte) rdr.GetValue(j) ...seems to be the only way to retrieve the value. But I can't figure out how to get the result into an int var.

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  • UTF-8 - Oracle issue

    - by goe
    I set my NLS_LANG variable as 'AMERICAN_AMERICA.AL32UTF8' in the perl file that connects to oracle and tries to insert the data. However when I insert a record with one value having this 'ñ' character the sql fails. But if I use 'Ñ' it inserts just fine. What am I doing wrong here?

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  • [R] How to create a data.frame with a unknow number of columns ?

    - by Olivier
    Hello I would like to create, in a function, a boucle to create a data.frame with a variable number of columns. WIth something like : a = c("a","b") b = c(list(1,2,3), list(4,5,6)) data.frame(a,b) I would like to get a data-frame like : a 1 2 3 b 4 5 6 Instead of I obtain : a 1 2 3 4 5 6 b 1 2 3 4 5 6 Thank you ! PS : I also try with rbind, but it's doesn't work...

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  • .net: does anyone know a free library to download nntp messages

    - by stighy
    hi folks, i'm using ip*works for download newsgroup message and insert them into a database... ipworks is "comfortable" to use because it automatically split nntp data return into different object (or variable). So i've "author" "date" "topic" "messagge" already splitted to my use. However ipworks isn't free and it cost a lot for my use.. so i'm asking you some component or code snippet to use to download and "manage" nntp messagges. Thanks in advance and regards!

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  • infix operation to postfix using stacks

    - by Chris De La O
    We are writing a program that needs to convert an infix operation (4 5/3) to postfix (4 5 3 / ) using stacks. however my convert to postfix does not work as it doesnt not output the postFix array that is supposed to store the conversion from infix notation to postfix notation. here is the code for the convertToPostix fuction. //converts infix expression to postfix expression void ArithmeticExpression::convertToPostfix(char *const inFix, char *const postFix) { //create a stack2 object named cow Stack2<char> cow; cout<<postFix; char thing = '('; //push a left parenthesis onto the stack cow.push(thing); //append a right parenthesis to the end of inFix array strcat(inFix, ")"); int i = 0;//declare an int that will control posFix position //if the stack is not empty if (!cow.isEmpty()) { //loop to run until the last character in inFix array for (int x = 0; inFix[x]!= '\0'; x++ ) { //if the inFix element is a digit if (isdigit(inFix[x])) { postFix[i]=inFix[x];//it is assigned to the next element in postFix array i++;//move on to next element in postFix } //if the inFix element is a left parenthesis else if (inFix[x]=='(') { cow.push(inFix[x]);//push it unto the stack } //if the inFix element is an operator else if (isOperator(inFix[x])) { char oper2 = inFix[x];//char variable holds inFix operator if (isOperator(cow.stackTop()))//if the top node in the stack is an operator { while (isOperator(cow.stackTop()))//and while the top node in the stack is an operator { char oper1 = cow.stackTop();//char variable holds node operator if(precedence( oper1, oper2))//if the node operator has higher presedence than node operator { postFix[i] = cow.pop();//we pop such operator and insert it in postFix array's next element cow.push(inFix[x]);//and push inFix operator unto the stack i++;//move to the next element in posFix } } } //if the top node is not an operator //we push the current inFix operator unto the top of the stack else cow.push(inFix[x]); } //if the inFix element is a right parenthesis else if (inFix[x]==')') { //we pop everything in the stack and insert it in postFix //until we arrive at a left paranthesis while (cow.stackTop()!='(') { postFix[i] = cow.pop(); i++; } //we then pop and discard left parenthesis cow.pop(); } } postFix[i]='\0'; //print !!postFix array!! (not stack) print();//code for this is just cout<<postFix; }

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  • Send data from Service to Widget on Android.

    - by Jose Vega
    I am writing a widget on Android 1.6 that shows the minutes that a person has used on the current month. The way I have it setup is by having a service that listens to the state of the phone and when the phone is picked up, it starts the timer and when the person hangs up, ends a timer. I would like to send this variable(long duration) over to my appWidgetProvider so I could update the edit text on it.

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  • How to search a MySQL database for a specific string

    - by Nadia
    I am trying to set up a search feature on my site that will only return exact matches to keyword entered by the user. So if the user searches "dog" I don't want an article titled "Doggy Style" to appear in the search results (just an example I don't really have an article by that name). This of course does exactly that: SELECT * FROM articles WHERE article_title LIKE '%$searchQuery%' $searchQuery here is a PHP variable taken from the user's input form. So is there any way to return only exact matches?

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  • Passing variables from PHP to Javascript back to PHP using Ajax.

    - by ObjectiveJ
    I hope this makes sesne, please bare with me. So I have a PHP page that contains variables, I have some radial boxes, and on click of them, it calculates a price for the item you have clicked on. I do this by activating a js function that I have passed some variables to. Like so. PHP: <?php $result = mssql_query("SELECT * FROM Segments ORDER BY 'Squares'"); if (!$result) { echo 'query failed'; exit; } while ($row = mssql_fetch_array($result)) { ?> <span><?php echo $row["Squares"]; ?></span><input name="squares" type="radio" onclick="ajaxCases('<?php echo $row["Squares"]; ?>', '<?php echo $row["StartCaseID"]; ?>', '<?php echo $row["StartMatrixPrice"]; ?>')" value="<?php echo $row["Squares"]; ?>"<?php if ($row["Squares"] == "1") { ?> checked="checked" <?php }else{ ?> checked="" <?php } ?>/> <?php } ?> As you can see onclick it goes to a function called ajaxcases, this function looks like this. function ajaxCases(squares,start,price){ $('#step1').html('<p style="margin:100px 0px 0px 100px"><img src="images/ajax-loader-bigindic.gif" width="32" height="32" alt="" /></p>'); $('#step1').load("ajax-styles.php?squares="+squares); prevId1 = ""; document.varsForm.caseid.value=start; $('#step1price').html('<span style="margin:0px 0px 0px 30px"><img src="images/ajax-loader-price.gif" width="24" height="24" alt="" /></span>'); $('#step1price').load("ajax-step1-price.php?Squares="+Squares); return true; } This then goes to a php page called ajax-step1-price.php and I try to recall the variable Squares. However it doesn't work, I thought it was a GET however that returns undefined. In Summary: I would like to know how to pass a variable from PHP to JS then back to PHP, or if someone could just tell me where I am going wrong that would be greatly appreciated.

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  • jquerry in rails

    - by Matthias Günther
    I'm iteration over records and want to create the toggle-options for records but I can't replace the div-id with the records: <% for bill in @bills % <% tmp = "test"% <%= link_to '&raquo now','#', :onclick = '$("#{tmp}").toggle();' % Instead of getting: &raquo now I'm getting: &raquo now So he isn't evaluation the ruby variable in the string. How can I do this? Thanks for your help and I'm new in jquerry.

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  • Visual C++ doesn't operator<< overload

    - by PierreBdR
    I have a vector class that I want to be able to input/output from a QTextStream object. The forward declaration of my vector class is: namespace util { template <size_t dim, typename T> class Vector; } I define the operator<< as: namespace util { template <size_t dim, typename T> QTextStream& operator<<(QTextStream& out, const util::Vector<dim,T>& vec) { ... } template <size_t dim, typename T> QTextStream& operator>>(QTextStream& in,util::Vector<dim,T>& vec) { .. } } However, if I ty to use these operators, Visual C++ returns this error: error C2678: binary '<<' : no operator found which takes a left-hand operand of type 'QTextStream' (or there is no acceptable conversion) A few things I tried: Originaly, the methods were defined as friends of the template, and it is working fine this way with g++. The methods have been moved outside the namespace util I changed the definition of the templates to fit what I found on various Visual C++ websites. The original friend declaration is: friend QTextStream& operator>>(QTextStream& ss, Vector& in) { ... } The "Visual C++ adapted" version is: friend QTextStream& operator>> <dim,T>(QTextStream& ss, Vector<dim,T>& in); with the function pre-declared before the class and implemented after. I checked the file is correctly included using: #pragma message ("Including vector header") And everything seems fine. Doesn anyone has any idea what might be wrong?

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  • Problem passing variables in php form.

    - by Joshxtothe4
    I have the following php form. I am trying to make it so that when the form is loaded, the values will be assigned the appropriate check- variable. This variable will contain either "checked or "". If it contains checked, the way it is displayed with the html should cause the relevant checkbox to be checked. As it is, the variables do not seem to be being passed. When I echo out $deleted or $notice from within the submitinfo branch, they are blank. Furthermore, nothing is being inserted into the database, and I am not getting any database error. How can I check this? <?php if (isset($_GET["cmd"])) $cmd = $_GET["cmd"]; else if (isset($_POST["cmd"])) $cmd = $_POST["cmd"]; else die("Invalid URL"); if (isset($_GET["pk"])) { $pk = $_GET["pk"]; } if (isset($_POST["deleted"])) { $deleted = $_POST["deleted"]; } if (isset($_POST["notice"])) { $notice = $_POST["notice"]; } $con = mysqli_connect("localhost","user","password", "db"); if (!$con) { echo "Can't connect to MySQL Server. Errorcode: %s\n". mysqli_connect_error(); exit; } $con->set_charset("utf8"); $getformdata = $con->query("select * from STATUS where ARTICLE_NO = '$pk'"); $checkDeleted = ""; $checkNotice = ""; while ($row = mysqli_fetch_assoc($getformdata)) { $checkDeleted = $row['deleted']; $checkNotice = $row['notice']; } if($cmd=="submitinfo") { $statusQuery = "INSERT INTO STATUS VALUES (?, ?)"; if ($statusInfo = $con->prepare($statusQuery)) { $statusInfo->bind_param("ss", $deleted, $notice); $statusInfo->execute(); $statusInfo->close(); echo "true"; } else { echo "false"; } print_r($con->error); } if($cmd=="EditStatusData") { echo "<form name=\"statusForm\" action=\"test.php\" method=\"post\" enctype=\"multipart/form-data\"> <h1>Editing information for auction: ".$pk."</h1> Löschung Ebay: <input type=\"checkbox\" name=\"deleted\" value=\"checked\" ".$checkDeleted." /> <br /> Abmahnung: <input type=\"checkbox\" name=\"notice\" value=\"checked\" ".$checkNotice." /> <br /> <input type=\"hidden\" name=\"cmd\" value=\"submitinfo\" /> <input name=\"Submit\" type=\"submit\" value=\"submit\" /> </form>"; } else { print_r($con->error); }

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  • SQL Query to get Count within a Stored Proc

    - by sia
    So i need to figure out how i can get a record count value and use that count as a new value to insert into a table. Ex: In My Stored Procedure @Count int What im looking for @Count to equal "select top (1) _fieldName from _someTable order by _fieldName Desc" Finally insert into _newTable (_fieldName) values (@Count) End I dont have to use a variable, just trying to demonstrate what im really trying to do. My SQL knowledge is pretty limited so no laughing, or smirking! ;)

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