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  • Proper usage of double and single quotes?

    - by Phox
    I'm talking about the performance increase here. From all I know you can echo variables in double quotes ("), like so: <?php echo "You are $yourAge years old"; ?> But single quotes will just return You are $yourAge years old. But what about performance differences? I've always gone by the rule that single quotes are faster because the PHP interpreter doesn't have to search through the string for variables. But I'm seeing more and more blog and forum posts on the web saying differently. Does anyone actually have any information on this subject? Perhaps benchmark tests or something?

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  • Java - Does null variable require space in memory

    - by Yatendra Goel
    class CheckStore { private String displayText; private boolean state; private String meaningfulText; private URL url; public CheckStore(String text, boolean state) { this.displayText = text; this.state = state; } : : } As I am initializing only two variables (displayText and state) in the constructor, Will the rest two variables (meaningfulText and url which will have the value null) will require space in memory to store null value. Q1. I think they will require space. If they will, then how much memory does a null value takes in the memory (like int takes 4 bytes). Q2. How much space a string takes in memory. I guess it will depend on the length of the string. So how much space a string takes of how much length?

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  • How to setup Math program

    - by Miles
    I'm needing to write a program (C#) that will allow the user to create generic formulas with variables and numbers. For example: D = A + (A - C / X)(7.8 - 6.6) F = E + (E - C / X)(7.8 - 6.6) FinalResult = (A + D)(0.9) + (E + F)(0.32) + B(0.1) + .023 where all variables would mean for me to go to a database and look something up based on values and return a number in its place. So A would be 2.12 for example (and the same for C and E) Whats the best way to structure this program? How would I make my program read these formulas? I've seen a little bit of the MathML but not sure how to get that started (or an example of it)

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  • Simple logic in javascript

    - by Saurabh
    I have four variables of type integer - var tip_1, tip_2, tip_3, tip_4; The value of these variables are getting fill by some other logic which is always between 1 to 10. I need to maintain a hash with variable name as "key" and value as "value" by following these rules - The variable with MAX value should be the first element in the hash and so on. e.g. if tip_1 = 4, tip_2 = 1, tip_3 = 2, tip_4 = 10 then hash should be something like, Hash = {tip_4, 10} {tip_1, 4} {tip_3, 2} {tip_1, 1} In case of tie following order should be considered - tip_1 tip_2 tip_3 tip_4;

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  • algorithm to combine data for linear fit?

    - by BoldlyBold
    I'm not sure if this is the best place to ask this, but you guys have been helpful with plenty of my CS homework in the past so I figure I'll give it a shot. I'm looking for an algorithm to blindly combine several dependent variables into an index that produces the best linear fit with an external variable. Basically, it would combine the dependent variables using different mathematical operators, include or not include each one, etc. until an index is developed that best correlates with my external variable. Has anyone seen/heard of something like this before? Even if you could point me in the right direction or to the right place to ask, I would appreciate it. Thanks.

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  • Post values in PHP Headers

    - by kumar
    Hi.. I want send some data to a remote webpage from my site. Actually it can be achieved through form hidden variables. but for security reason, i want set as post variables in header and then send to that webpage. i use this code $post_data = 'var1=123&var2=456'; $content_length = strlen($post_data); header('POST http://localhost/testing/test.php HTTP/1.1'); header('Host: localhost'); header('Connection: close'); header('Content-type: application/x-www-form-urlencoded'); header('Content-length: ' . $content_length); header($post_data); but my code doesn't work properly. help me...

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  • Confused with objects in Ruby

    - by David
    Ruby Newbie here, I understand that everything is an object in Ruby, one thing that I wasn't sure about was understanding Variables. Variables basically give reference to objects (correct me if I'm wrong). During an instructional video, the teacher did a demonstration which went as below: (irb) a = 100 ==> 100 b = a ==> 100 b ==> 100 This part I get, makes total sense. Then he did a = 50 ==> 50 b ==> 100 If B is supposed to point to what a was set which was a 100, why does b still point to 100 if a has now been set as 50?

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  • PHP class that changes an image and reloads the page not displaying new image in Internet Explorer

    - by Stuart
    I have a class that runs a function when the image is clicked on to display an additional image. This function produces a linked div tag that reloads the page with a set of variables that then produces another image. The image is set as a background image on a large div tag behind the linked div tags to give the same effect as an image map but without using an image map or a SVG. This works perfectly in Chrome and Firefox but will not display the new image in Internet Explorer until you F5 the page again with the get variables in the URL? Does anyone know how to fix this issue so that it works in IE the same as the other browsers? Many thanks.

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  • Member variable in C++ class that is always constant for all objects of that class?

    - by user1799323
    I'm constructing a class where I have three member variables that I want to always be the same value NO MATTER WHAT. I have class foo{ public: double var_1, var_2, var_3; double x=1, y=2, z=3; [functions go here] }; that gave me an error since I can't initialize a variable like that. But I want x, y and z to always be 1, 2 and 3 respectively. I tried defining them outside the class but that doesn't work since I want them to be member variables of the class. How do I do this?

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  • What is the Sql Server equivalent for Oracle's DBMS_ASSERT?

    - by dotNetYum
    DBMS_ASSERT is one of the keys to prevent SQL injection attacks in Oracle. I tried a cursory search...is there any SQL Server 2005/2008 equivalent for this functionality? I am looking for a specific implementation that has a counterpart of all the respective Oracle package members of DBMS_ASSERT. NOOP SIMPLE_SQL_NAME QUALIFIED_SQL_NAME SCHEMA_NAME I know the best-practices of preventing injection...bind variables...being one of them. But,in this question I am specifically looking for a good way to sanitize input...in scenarios where bind-variables were not used. Do you have any specific implemetations? Is there a library that actually is a SQL Server Port of the Oracle package?

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  • Firing events in script task

    - by Anonymouslemming
    I've got an SSIS project where I am constructing an SQL command based on some variables. I'm constructing the command in a script task, and want to output the constructed SQL to the 'Execution Results' window. I am trying to do this using a FireInformation line from inside my script as follows: Dts.Events.FireInformation(99, "test", "Make this event appear!", "", 0, true); However, in the script editor when editing ScriptMain.cs, that line is underlined in red, and on mouseover, I get the following message: Error: The best overloaded method match for 'Microsoft.SqlServer.Dts.Tasks.ScriptTask.EventsObjectWrapper.FireInformation(int, string, string, string, int, ref bool') has some invalid arguments As a result, my script does not compile and I cannot execute it. Any idea what I'm doing wrong here, or what I need to change to be able to see the values of my variables at this point in the Execution output?

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  • Access static constant variable from multiple threads in C

    - by user325519
    I have some experience with multithread programming under Linux (C/C++ & POSIX threads), however most obvious cases are sometimes very complicated. I have several static constant variables (global and function local) in my code, can I access them simultaneously from multiple threads without using mutexes? Because I don't modify them it should be ok, but it's always better to ask. I have to do heavy speed optimization, so even as fast operations as mutex lock/unlock are quite expensive for me, especially because my application is going to access these variables form long loops.

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  • How does the CLR (.NET) internally allocate and pass around custom value types (structs)?

    - by stakx
    Question: Do all CLR value types, including user-defined structs, live on the evaluation stack exclusively, meaning that they will never need to be reclaimed by the garbage-collector, or are there cases where they are garbage-collected? Background: I have previously asked a question on SO about the impact that a fluent interface has on the runtime performance of a .NET application. I was particuarly worried that creating a large number of very short-lived temporary objects would negatively affect runtime performance through more frequent garbage-collection. Now it has occured to me that if I declared those temporary objects' types as struct (ie. as user-defined value types) instead of class, the garbage collector might not be involved at all if it turns out that all value types live exclusively on the evaluation stack. What I've found out so far: I did a brief experiment to see what the differences are in the CIL generated for user-defined value types and reference types. This is my C# code: struct SomeValueType { public int X; } class SomeReferenceType { public int X; } . . static void TryValueType(SomeValueType vt) { ... } static void TryReferenceType(SomeReferenceType rt) { ... } . . var vt = new SomeValueType { X = 1 }; var rt = new SomeReferenceType { X = 2 }; TryValueType(vt); TryReferenceType(rt); And this is the CIL generated for the last four lines of code: .locals init ( [0] valuetype SomeValueType vt, [1] class SomeReferenceType rt, [2] valuetype SomeValueType <>g__initLocal0, // [3] class SomeReferenceType <>g__initLocal1, // why are these generated? [4] valuetype SomeValueType CS$0$0000 // ) L_0000: ldloca.s CS$0$0000 L_0002: initobj SomeValueType // no newobj required, instance already allocated L_0008: ldloc.s CS$0$0000 L_000a: stloc.2 L_000b: ldloca.s <>g__initLocal0 L_000d: ldc.i4.1 L_000e: stfld int32 SomeValueType::X L_0013: ldloc.2 L_0014: stloc.0 L_0015: newobj instance void SomeReferenceType::.ctor() L_001a: stloc.3 L_001b: ldloc.3 L_001c: ldc.i4.2 L_001d: stfld int32 SomeReferenceType::X L_0022: ldloc.3 L_0023: stloc.1 L_0024: ldloc.0 L_0025: call void Program::TryValueType(valuetype SomeValueType) L_002a: ldloc.1 L_002b: call void Program::TryReferenceType(class SomeReferenceType) What I cannot figure out from this code is this: Where are all those local variables mentioned in the .locals block allocated? How are they allocated? How are they freed? Why are so many anonymous local variables needed and copied to-and-fro only to initialize my two local variables rt and vt?

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  • Passing Session[] and Request[] to Methods in C#

    - by NYARROW
    In C#, How do you pass the Session[] and Request[] objects to a method? I would like to use a method to parse out Session and Request paramaters for a .aspx page to reduce the size of my Page_Load method. I am passing quite a few variables, and need to support both POSTand GET methods. For most calls, not all variables are present, so I have to test every variable multiple ways, and the code gets long... This is what I am trying to do, but I can't seem to properly identify the Session and Request paramaters (this code will not compile, because the arrays are indexed by number) static string getParam( System.Web.SessionState.HttpSessionState[] Session, System.Web.HttpRequest[] Request, string id) { string rslt = ""; try { rslt = Session[id].ToString(); } catch { try { rslt = Request[id].ToString(); } catch { } } return rslt; } From Page_Load, I want to call this method as follows to retrieve the "MODE" paramater: string rslt; rslt = getParam(Session, Request, "MODE"); Thanks!

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  • 'Caching' a large table in ASP.NET

    - by TheNewGuy
    I understand that each page refresh, especially in 'AjaxLand', causes my back-end/code-behind class to be called from scratch... This is a problem because my class (which is a member object in System.Web.UI.Page) contains A LOT of data that it sources from a database. So now every page refresh in AjaxLand is causing me to making large backend DB calls, rather than just to reuse a class object from memory. Any fix for this? Is this where session variables come into play? Are session variables the only option I have to retain an object in memory that is linked to a single-user and a single-session instance?

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  • Can't get a List(Of <my class>) from a Dictionary in .NET?

    - by magsto
    I have a Dictionary with key of type UInteger and the value is List(Of Session) where the (Public) class Session contains a couple of variables and a constructor (Public Sub New(...)). Some of the variables in my Session class is: Private count As Integer Private StartDate As Date Private Values As List(Of Integer) and a couple of methods like: Friend Sub Counter(ByVal c as Integer) count += c End Sub There is no problem to add values to the Dictionary: Dim Sessions As New List(Of Session) Dim dict As New Dictionary(Of Integer, Sessions) then some code to fill up a couple of Session objects in Sessions (not shown here) and then: dict.Add(17, Sessions) 'No problem Sessions.Clear() Sessions = dict(17) 'This doesn't return anything! The Sessions object is empty even if the code doesn't returned any error. Is my class Session to compex to be stored in a Dictionary?

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  • int i vs int index etc. Which one is better?

    - by Earlz
    Coming from a C background I've always used int i for generic loop variables. Of course in big nested loops or other complex things I may use a descriptive name but which one had you rather see? int i; for(i=0;i<Controls.Count;i++){ DoStuff(Controls[i]); } or int index; for(index=0;index<Controls.Count;index++){ DoStuff(Controls[index]); } In the current project I am working on there are both of these styles and index being replaced by ndx. Which one is better? Is the i variable too generic? Also what about the other C style names? i, j, k Should all of these be replaced by actual descriptive variables?

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  • Problem with sending "SetCookie" first in php code

    - by Camran
    According to this manual: http://us2.php.net/setcookie I have to set the cookie before anything else. Here is my cookie code: if (isset($_COOKIE['watched_ads'])){ $expir = time()+1728000; //20 days $ad_arr = unserialize($_COOKIE['watched_ads']); $arr_elem = count($ad_arr); if (in_array($ad_id, $ad_arr) == FALSE){ if ($arr_elem>10){ array_shift($ad_arr); } $ad_arr[]=$ad_id; setcookie('watched_ads', serialize($ad_arr), $expir, '/'); } } else { $expir = time()+1728000; //20 days $ad_arr[] = $ad_id; setcookie('watched_ads', serialize($ad_arr), $expir, '/'); } As you can see I am using variables in setting the cookie. The variables comes from a mysql_query and I have to do the query first. But then, if I do, I will get an error message: Cannot modify header information - headers already sent by ... The error points to the line where I set the cookie above. What should I do?a

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  • Read options from file

    - by Devel
    I would like to write a function which will read values from a text file and write them to variables. For example my file is: mysql_server localhost mysql_user root mysql_passworg pospaz mysql_database testgenerator log log.txt username admin password abcd and I have the same variables as the first word in the line. So how to make the function read data from file and do sth like this: char *mysql_server = localhost; char *mysql_user = root; ... I have no idea even how to start writing it...

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  • Performance implications of using a variable versus a magic number

    - by Nathan
    I'm often confused by this. I've always been taught to name numbers I use often using variables or constants, but if it reduces the efficiency of the program, should I still do it? Heres an example: private int CenterText(Font font, PrintPageEventArgs e, string text) { int recieptCenter = 125; int stringLength = Convert.ToInt32(e.Graphics.MeasureString(text, font)); return recieptCenter - stringLength / 2; } The above code is using named variables, but runs slower then this code: private int CenterText(Font font, PrintPageEventArgs e, string text) { return 125 - Convert.ToInt32(e.Graphics.MeasureString(text, font) / 2); } In this example, the difference in execution time is minimal, but what about in larger blocks of code?

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  • PHP - turning register globals off, what is the best way to go about fixing the code?

    - by user187809
    I am working on a old code base, where programmers assumed that register_globals will always be on. Hence variables are used without $_GET or $_POST prefix, pretty much in every page (the code base is huge, hundreds of scripts). I tried turning it off, but the very first script (login script) goes on an infinite loop. I understand that going through one script at a time, and one line at a time and fixing the variables is probably the only option (adding the prefix $_GET or $_POST as the case may be). Has anyone does this before? How did you go about doing it? Any advice?

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  • Is there a %in% operator accros multiple columns

    - by RobinLovelace
    Imagine you have two data frames df1 <- data.frame(V1 = c(1, 2, 3), v2 = c("a", "b", "c")) df2 <- data.frame(V1 = c(1, 2, 2), v2 = c("b", "b", "c")) Here's what they look like, side by side: > cbind(df1, df2) V1 v2 V1 v2 1 1 a 1 b 2 2 b 2 b 3 3 c 2 c You want to know which observations are duplicates, across all variables. This can be done by pasting the cols together and then using %in%: df1Vec <- apply(df1, 1, paste, collapse= "") df2Vec <- apply(df2, 1, paste, collapse= "") df2Vec %in% df1Vec [1] FALSE TRUE FALSE The second observation is thus the only one in df2 and also in df1. Is there no faster way of generating this output - something like %IN%, which is %in% across multiple variables, or should we just be content with the apply(paste) solution?

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  • C++ class is not recognizing string data type

    - by reallythecrash
    I'm working on a program from my C++ textbook, and this this the first time I've really run into trouble. I just can't seem to see what is wrong here. Visual Studio is telling me Error: identifier "string" is undefined. I separated the program into three files. A header file for the class specification, a .cpp file for the class implementation and the main program file. These are the instructions from my book: Write a class named Car that has the following member variables: year. An int that holds the car's model year. make. A string that holds the make of the car. speed. An int that holds the car's current speed. In addition, the class should have the following member functions. Constructor. The constructor should accept the car's year and make as arguments and assign these values to the object's year and make member variables. The constructor should initialize the speed member variable to 0. Accessors. Appropriate accessor functions should be created to allow values to be retrieved from an object's year, make and speed member variables. There are more instructions, but they are not necessary to get this part to work. Here is my source code: // File Car.h -- Car class specification file #ifndef CAR_H #define CAR_H class Car { private: int year; string make; int speed; public: Car(int, string); int getYear(); string getMake(); int getSpeed(); }; #endif // File Car.cpp -- Car class function implementation file #include "Car.h" // Default Constructor Car::Car(int inputYear, string inputMake) { year = inputYear; make = inputMake; speed = 0; } // Accessors int Car::getYear() { return year; } string Car::getMake() { return make; } int Car::getSpeed() { return speed; } // Main program #include <iostream> #include <string> #include "Car.h" using namespace std; int main() { } I haven't written anything in the main program yet, because I can't get the class to compile. I've only linked the header file to the main program. Thanks in advance to all who take the time to investigate this problem for me.

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  • Problem carrying Session over to other pages

    - by AAA
    I am able to login a user, but while processing to the next page (memebers area) I can't display any user info let alone print the $_SESSION[email]. I am not sure what's up. Below is the login code and the testing members are page. Login page: session_start(); //also in a real app you would get the id dynamically $sql = "select `email`, `password` from `accounts` where `email` = '$_POST[email]'"; $query = mysql_query($sql) or die ("Error: ".mysql_error()); while ($row = mysql_fetch_array($query)){ $email = $row['email']; $secret = $row['password']; //we will echo these into the proper fields } mysql_free_result($query); // Process the POST variables $email = $_POST["email"]; //Variables $_SESSION["email"] = $_POST["email"]; $secret = $info['password']; //Checks if there is a login cookie if(isset($_COOKIE['ID_my_site'])) //if there is, it logs you in and directes you to the members page { $email = $_COOKIE['ID_my_site']; $pass = $_COOKIE['Key_my_site']; $check = mysql_query("SELECT email, password FROM accounts WHERE email = '$email'")or die(mysql_error()); while($info = mysql_fetch_array( $check )) { if (@ $info['password'] != $pass) { } else { header("Location: home.php"); } } } //if the login form is submitted if (isset($_POST['submit'])) { // if form has been submitted // makes sure they filled it in if(!$_POST['email'] | !$_POST['password']) { die('You did not fill in a required field.'); } // checks it against the database if (!get_magic_quotes_gpc()) { $_POST['email'] = addslashes($_POST['email']); } $check = mysql_query("SELECT email,password FROM accounts WHERE email = '".$_POST['email']."'")or die(mysql_error()); //Gives error if user dosen't exist $check2 = mysql_num_rows($check); if ($check2 == 0) { die('That user does not exist in our database. <a href=add.php>Click Here to Register</a>'); } while($info = mysql_fetch_array( $check )) //gives error if the password is wrong if (@ $_POST['password'] != $info['password']) { die('Incorrect password, please try again'); } else { // if login is ok then we add a cookie $_POST['email'] = stripslashes($_POST['email']); $hour = time() + 3600; setcookie(ID_my_site, $_POST['email'], $hour); setcookie(Key_my_site, $_POST['password'], $hour); //then redirect them to the members area header("Location: home.php"); } } } else { // if they are not logged in ?> <?php } ?> home.php session_start(); if(!isset($_SESSION['email'])) { header('Location: login_test3.php'); die('<a href="login_test3.php">Login first!</a>'); } //Variables $_SESSION["email"] = $email; print $_SESSION['name']; UPDATE Just realized the existing code gets in to the home.php file but will not echo anything. But as soon as you hit refresh the session is gone.

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