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  • Scanning, Checking, Converting, Copying values ... How to ? -- C --

    - by ZaZu
    Hi there, Its been a while now and im still trying to get a certain code to work. I asked some question about different commands etc. before, but now I hope this is the final one (combining all questions in one code). I basically want to : *Scan an input (should be character ? ) *Check if its a number *If not, return error *Convert that character into a float number *Copy the value to another variable ( I called it imp here) Here is what I came up with : #include<stdio.h> #include<stdlib.h> #include<ctype.h> main(){ int digits; float imp=0; int alpha; do{ printf("Enter input\n\n"); scanf("\n%c",&alpha); digits=isdigit(alpha); if(digits==0){ printf("error\n\n"); } imp=atof(alpha); }while(digits==0); } The problem is this code does not work at all ... It gives me that atof must be of a const char and whenever I try changing it around, it just keeps failing. I am frustrated and forced to ask here, because I believe I have tried alot and I keep failing, but I wont be relieved until I get it to work xD So I really need your help guys. Please tell me why isnt this code working, what am I doing wrong ? I am still learning C and really appreciate your help :)

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  • Entity framework with Linq to Entities performance

    - by mare
    If I have a static method like this public static string GetTicClassificationTitle(string classI, string classII, string classIII) { using (TicDatabaseEntities ticdb = new TicDatabaseEntities()) { var result = from classes in ticdb.Classifications where classes.ClassI == classI where classes.ClassII == classII where classes.ClassIII == classIII select classes.Description; return result.FirstOrDefault(); } } and use this method in various places in foreach loops or just plain calling it numerous times, does it create and open new connection every time? If so, how can I tackle this? Should I cache the results somewhere, like in this case, I would cache the entire Classifications table in Memory Cache? And then do queries vs this cached object? Or should I make TicDatabaseEntities variable static and initialize it at class level? Should my class be static if it contains only static methods? Because right now it is not.. Also I've noticed that if I return result.First() instead of FirstOrDefault() and the query does not find a match, it will issue an exception (with FirstOrDefault() there is no exception, it returns null). Thank you for clarification.

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  • sum of square of each elements in the vector using for_each

    - by pierr
    Hi, As the function accepted by for_each take only one parameter (the element of the vector), I have to define a static int sum = 0 somewhere so that It can be accessed after calling the for_each . I think this is awkward. Any better way to do this (still use for_each) ? #include <algorithm> #include <vector> #include <iostream> using namespace std; static int sum = 0; void add_f(int i ) { sum += i * i; } void test_using_for_each() { int arr[] = {1,2,3,4}; vector<int> a (arr ,arr + sizeof(arr)/sizeof(arr[0])); for_each( a.begin(),a.end(), add_f); cout << "sum of the square of the element is " << sum << endl; } In Ruby, We can do it this way: sum = 0 [1,2,3,4].each { |i| sum += i*i} #local variable can be used in the callback function puts sum #=> 30 Would you please show more examples how for_each is typically used in practical programming (not just print out each element)? Is it possible use for_each simulate 'programming pattern' like map and inject in Ruby (or map /fold in Haskell). #map in ruby >> [1,2,3,4].map {|i| i*i} => [1, 4, 9, 16] #inject in ruby [1, 4, 9, 16].inject(0) {|aac ,i| aac +=i} #=> 30 EDIT: Thank you all. I have learned so much from your replies. We have so many ways to do the same single thing in C++ , which makes it a little bit difficult to learn. But it's interesting :)

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  • CSS positioning div above another div when not in that order in the HTML

    - by devmode
    Given a template where the HTML cannot be modified because of other requirements, how is it possible to display a div above another div when they are not in that order in the HTML and both divs contain data that could produce a varying height and width. HTML: <div id="wrapper"     <div id="firstDiv"         Content to be below in this situation     </div     <div id="secondDiv"         Content to be above in this situation     </div </div Other elements Hopefully it is obvious that the desired result is: Content to be above in this situation Content to be below in this situation Other elements When the dimensions are fixed it easy to position them where needed, but I need some ideas for when the content is variable. For the sake of this scenario, please just consider the width to be 100% on both. Edit: A CSS solution is the most ideal solution. Thank you for the Javascript options mentioned. Without getting too wordy about what or why (or who) ... I am specifically looking for a CSS only solution (and it will probably have to be met with other solutions if that doesn't pan out). One more ... there are other elements following this. A good suggestion was mentioned given the limited scenario I demonstrated -- given that it might be the best answer, but I am looking to also make sure elements following this aren't impacted.

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  • How to duplicate all data in a table except for a single column that should be changed.

    - by twiga
    I have a question regarding a unified insert query against tables with different data structures (Oracle). Let me elaborate with an example: tb_customers ( id NUMBER(3), name VARCHAR2(40), archive_id NUMBER(3) ) tb_suppliers ( id NUMBER(3), name VARCHAR2(40), contact VARCHAR2(40), xxx, xxx, archive_id NUMBER(3) ) The only column that is present in all tables is [archive_id]. The plan is to create a new archive of the dataset by copying (duplicating) all records to a different database partition and incrementing the archive_id for those records accordingly. [archive_id] is always part of the primary key. My problem is with select statements to do the actual duplication of the data. Because the columns are variable, I am struggling to come up with a unified select statement that will copy the data and update the archive_id. One solution (that works), is to iterate over all the tables in a stored procedure and do a: CREATE TABLE temp as (SELECT * from ORIGINAL_TABLE); UPDATE temp SET archive_id=something; INSERT INTO temp (select * from temp); DROP TABLE temp; I do not like this solution very much as the DDL commands muck up all restore points. Does anyone else have any solution?

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  • Multithreading using pthread in C++ with shared variables

    - by Saviour Self
    I'm new to threading (and C/C++ for that matter), and I'm attempting to use multiple threads to access shared variables. In the main, I've created a variable char inputarray[100]; Thread 1: This thread will be reading data from stdin in 2 byte bursts, and appending them to the inputarray. (input by feeding a file in) Thread 2: This thread will be reading data 1 byte at a time, performing a calculation, and putting its data into an output array. Thread 3: This thread will be outputting data from the output array in 2 byte bursts. (stdout) I've attempted the input part and got it working by passing a struct, but would like to do it without using a struct, but it has been giving me problems. If I can get input down, I'm sure I'll be able to use a similar strategy to complete output. Any help would be greatly appreciated. Below is a rough template for the input thread. #include <stdio.h> #include <pthread.h> using namespace std; void* input(void* arg) { char reading[3]; fread(reading,1,2,stdin); //append to char inputarray[]..??? } int main() { char inputarray[100]; pthread_t t1; pthread_create(&t1, NULL, &input, &inputarray); void *result; pthread_join(t1,&result); return 0; }

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  • parsing of mathematical expressions

    - by gcc
    (in c90) (linux) input: sqrt(2 - sin(3*A/B)^2.5) + 0.5*(C*~(D) + 3.11 +B) a b /*there are values for a,b,c,d */ c d input: cos(2 - asin(3*A/B)^2.5) +cos(0.5*(C*~(D)) + 3.11 +B) a b /*there are values for a,b,c,d */ c d input: sqrt(2 - sin(3*A/B)^2.5)/(0.5*(C*~(D)) + sin(3.11) +ln(B)) /*max lenght of formula is 250 characters*/ a b /*there are values for a,b,c,d */ c /*each variable with set of floating numbers*/ d As you can see infix formula in the input depends on user. My program will take a formula and n-tuples value. Then it calculate the results for each value of a,b,c and d. If you wonder I am saying ;outcome of program is graph. /sometimes,I think i will take input and store in string. then another idea is arise " I should store formula in the struct" but i don't know how I can construct the code on the base of structure./ really, I don't know way how to store the formula in program code so that I can do my job. can you show me? /* a,b,c,d is letters cos,sin,sqrt,ln is function*/

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  • Zend XML parsing

    - by Vincent
    I have an xml file called error.xml like this: <?xml version="1.0" encoding="UTF-8"?> <errorList> <error> <code>0</code> <desc>Fault</desc> <ufmessage>Fault</ufmessage> </error> <error> <code>1</code> <desc>Unknown</desc> <ufmessage>Unknown</ufmessage> </error> <error> <code>2</code> <desc>Internal Error</desc> <ufmessage>Internal Error</ufmessage> </error> </errorList> I am using Zend and have the above xml file stored in a Zend Registry variable called "apperrors" like this: $apperrors = new Zend_Config_Xml( 'error.xml'); Zend_Registry::set('apperrors', $apperrors->errorList); If my code throws an error code of 2, I want a snippet of code to check the error code with "code" key in "apperrors" array and echo the ufmessage value corresponding to it. How can I do this? Ex: //Error thrown by the code. Hardcoded for now... $errorThrownByCode = 2; //Get the Zend Registry value for all errors $errorList = Zend_Registry::get('apperrors'); //Write some code to compare $errorThrownByCode with $errorList->error->code //If found echo $errorList->error->ufmessage, else echo "An Unknown error occured"; Thanks

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  • Error 2025: The supplied DisplayObject must be a child of the caller

    - by Mocca
    Hi, sorry, new to actionscript 3. I have a display() function for an object rotator(image based like a QT object movie). It first saves the current image in a helper variable and then allocates a new image, from the library, beneath the old one. To get a nice crossfade effect, the old image's alpha is looped down via enter_frame and then removed. Which is where there seems to be an issue with the display list, maybe recognizing oldImg's value as being already added? (it's not a first pass error) Btw, do i have to remove the old image or can i leave it, for when it's being called up via the mouse position again? (the image number can get fairly large) Does anyone have further insight? Thanks! function display(num:Number):void //num: image number { ... oldImg = newImg; ClassReference = getDefinitionByName("Class"+num) as Class; imgBD = new ClassReference(0,0); newImg = new Bitmap(imgBD); images.addChild(newImg); newImg.x=0; newImg.y=0; } function onEnter(evt:Event):void { if (oldImg) { if (oldImg.alpha > 0) oldImg.alpha -= 0.15; **else images.removeChild(oldImg);** } ... }

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  • Why does animate not work for the first few 'selections' of my next button?

    - by Josiah
    I'll just start right off the bat and say I'm fairly new to JQuery, so if you see some glaring issues with my code....let me know what I'm doing wrong! Either way, I've been working on a script to fade divs in and out using the z-index and animate. It "works" after about 2-3 clicks, but the first two clicks do not fade or animate as I was hoping....why is that? I'll just throw javascript up here, but if you need/want more code, just let me know. Thanks! $(document).ready(function() { //Slide rotation/movement variables var first = $('#main div.slide:first').attr('title'); var last = $('#main div.slide').length; //Needed for the next/prev buttons var next; //Set the first div to the front, and variable for first div var $active = $('#main div.slide[title='+first+']'); //Hide the links until the div is hovered over and take them away when mouse leaves $('#main').children('a').hide(); $('#main').mouseenter(function() { $('#main').children('a').fadeIn(750); }).mouseleave(function() { $('#main').children('a').fadeOut(750); }); $active.css('z-index', '4'); $('#main #next').click(function() { if ((next = parseInt($active.attr('title')) + 1) > last) { next = 1; } $active.css('z-index', '0').stop().animate({opacity: 0}, 1000); $active = $('#main div[title='+next+']').css('z-index', '4').stop().animate({opacity : 1}, 1000); }); });

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  • numpy array assignment problem

    - by Sujan
    Hi All: I have a strange problem in Python 2.6.5 with Numpy. I assign a numpy array, then equate a new variable to it. When I perform any operation to the new array, the original's values also change. Why is that? Please see the example below. Kindly enlighten me, as I'm fairly new to Python, and programming in general. -Sujan >>> import numpy as np >>> a = np.array([[1,2],[3,4]]) >>> b = a >>> b array([[1, 2], [3, 4]]) >>> c = a >>> c array([[1, 2], [3, 4]]) >>> c[:,1] = c[:,1] + 5 >>> c array([[1, 7], [3, 9]]) >>> b array([[1, 7], [3, 9]]) >>> a array([[1, 7], [3, 9]])

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  • Wordpress paths issue

    - by Martin
    I have set a crawler up in wordpress which grabs stocks data and writes to file which when a user enters a symbol/ticker the variable is read and if it matches the data of a previous crawl for that particular companies data will echo the text file on page, if no data is found the crawler then sets off grabs it and writes to file to save for the next time that symbol is used. The problem im having is that everything works groovey apart from one thing, when the content is written to file it saves it in the WP root and not inside a subfolder of the theme, basicaly this means that root becomes untidy very quickly and also should the theme be used on another site then its not practical as some important info is missing. I have tried bloginfo and absolute both return the same failure. This is the code i am using to write to file, like i say it works apart from writing the file into root. <?php $CompDetails = "http://www.devserverurl.com/mattv1/wp-content/themes/stocks/tools/modules/Stock_Quote/company_details/$Symbol.txt"; if (file_exists($CompDetails)) {} else { include ('crawler_file.php'); $html = file_get_html("http://targeturl.com/research/stocks/snapshot/snapshot.asp?ticker=$Symbol:US"); $es = $html->find('div[class="detailsDataContainerLt"]'); $tickerdetails = ("$es[0]"); $FileHandle2 = fopen($CompDetails, 'w') or die("can't open file"); fwrite($FileHandle2, $tickerdetails); fclose($FileHandle2); } ?> edit below, have also tried this and the same happens as above <?php if (file_exists($_SERVER['DOCUMENT_ROOT'] . "/wp-content/themes/stocks/tools/modules/Stock_Quote/company_details/$Symbol.txt")) {} else { include ('crawler_file.php'); $html = file_get_html("http://targeturl.com/research/stocks/snapshot/snapshot.asp?ticker=$Symbol:US"); $es = $html->find('div[class="detailsDataContainerLt"]'); $tickerdetails = ("$es[0]"); $FileHandle2 = fopen($_SERVER['DOCUMENT_ROOT'] . "/wp-content/themes/stocks/tools/modules/Stock_Quote/company_details/$Symbol.txt", 'w') or die("can't open file"); fwrite($FileHandle2, $tickerdetails); fclose($FileHandle2); } ?>

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  • str_replace() and strpos() for arrays?

    - by Josh
    I'm working with an array of data that I've changed the names of some array keys, but I want the data to stay the same basically... Basically I want to be able to keep the data that's in the array stored in the DB, but I want to update the array key names associated with it. Previously the array would have looked like this: $var_opts['services'] = array('foo-1', 'foo-2', 'foo-3', 'foo-4'); Now the array keys are no longer prefixed with "foo", but rather with "bar" instead. So how can I update the array variable to get rid of the "foos" and replace with "bars" instead? Like so: $var_opts['services'] = array('bar-1', 'bar-2', 'bar-3', 'bar-4'); I'm already using if(isset($var_opts['services']['foo-1'])) { unset($var_opts['services']['foo-1']); } to get rid of the foos... I just need to figure out how to replace each foo with a bar. I thought I would use str_replace on the whole array, but to my dismay it only works on strings (go figure, heh) and not arrays.

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  • Django throws 404 at generic views

    - by x0rg
    I'm trying to get the generic views for a date-based archive working in django. I defined the urls as described in a tutorial, but django returns a 404 error whenever I want to access an url with a variable (such as month or year) in it. It don't even produces a TemplateDoesNotExist-execption. Normal urls without variables work fine. Here's my urlconf: from django.conf.urls.defaults import * from zurichlive.zhl.models import Event info_dict = { 'queryset': Event.objects.all(), 'date_field': 'date', 'allow_future': 'True', } urlpatterns += patterns('django.views.generic.date_based', (r'events/(?P<year>d{4})/(?P<month>[a-z]{3})/(?P<day>w{1,2})/(?P<slug>[-w]+)/$', 'object_detail', dict(info_dict, slug_field='slug',template_name='archive/detail.html')), (r'^events/(?P<year>d{4})/(?P<month>[a-z]{3})/(?P<day>w{1,2})/(?P<slug>[-w]+)/$', 'object_detail', dict(info_dict, template_name='archive/list.html')), (r'^events/(?P<year>d{4})/(?P<month>[a-z]{3})/(?P<day>w{1,2})/$','archive_day',dict(info_dict,template_name='archive/list.html')), (r'^events/(?P<year>d{4})/(?P<month>[a-z]{3})/$','archive_month', dict(info_dict, template_name='archive/list.html')), (r'^events/(?P<year>)/$','archive_year', dict(info_dict, template_name='archive/list.html')), (r'^events/$','archive_index', dict(info_dict, template_name='archive/list.html')), ) When I access /events/2010/may/12/this-is-a-slug I should get to the detail.html template, but instead I get a 404. What am I doing wrong?

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  • How to call a generic method with an anonymous type involving generics?

    - by Alex Black
    I've got this code that works: def testTypeSpecialization = { class Foo[T] def add[T](obj: Foo[T]): Foo[T] = obj def addInt[X <% Foo[Int]](obj: X): X = { add(obj) obj } val foo = addInt(new Foo[Int] { def someMethod: String = "Hello world" }) assert(true) } But, I'd like to write it like this: def testTypeSpecialization = { class Foo[T] def add[X, T <% Foo[X](obj: T): T = obj val foo = add(new Foo[Int] { def someMethod: String = "Hello world" }) assert(true) } This second one fails to compile: no implicit argument matching parameter type (Foo[Int]{ ... }) = Foo[Nothing] was found. Basically: I'd like to create a new anonymous class/instance on the fly (e.g. new Foo[Int] { ... } ), and pass it into an "add" method which will add it to a list, and then return it The key thing here is that the variable from "val foo = " I'd like its type to be the anonymous class, not Foo[Int], since it adds methods (someMethod in this example) Any ideas? I think the 2nd one fails because the type Int is being erased. I can apparently 'hint' the compiler like this: def testTypeSpecialization = { class Foo[T] def add[X, T <% Foo[X]](dummy: X, obj: T): T = obj val foo = add(2, new Foo[Int] { def someMethod: String = "Hello world" }) assert(true) }

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  • Javascript nested functions not returning

    - by Achintha Samindika
    I'm building a phonehap application. I'm using an web sql and everything works fine till data retival. function getItemGroups(){ var items_groups = new Array(); var db = window.openDatabase("merbokDB", "1.0", "MerbokDB", 5232394); db.transaction( function(tx){ tx.executeSql('SELECT * FROM item_groups',[], function(tx,result){ if(result.rows.length > 0){ var len = result.rows.length; for (var i=0; i<len; i++){ items_groups.push(result.rows.item(i).item_group); } console.log(items_groups.join()); } } ,errorCB); }, errorCB); return items_groups; } var myproducts = getItemGroups(); My problem was when I run the code "myproducts" variable is blank. but the I can see console.log(items_groups.join()); following line printing the values in console. Is I'm wrong in the way I returning?

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  • What's the best way to communicate the purpose of a string parameter in a public API?

    - by Dave
    According to the guidance published in New Recommendations for Using Strings in Microsoft .NET 2.0, the data in a string may exhibit one of the following types of behavior: A non-linguistic identifier, where bytes match exactly. A non-linguistic identifier, where case is irrelevant, especially a piece of data stored in most Microsoft Windows system services. Culturally-agnostic data, which still is linguistically relevant. Data that requires local linguistic customs. Given that, I'd like to know the best way to communicate which behavior is expected of a string parameter in a public API. I wasn't able to find an answer in the Framework Design Guidelines. Consider the following methods: f(string this_is_a_linguistic_string) g(string this_is_a_symbolic_identifier_so_use_ordinal_compares) Is variable naming and XML documentation the best I can do? Could I use attributes in some way to mark the requirements of the string? Now consider the following case: h(Dictionary<string, object> dictionary) Note that the dictionary instance is created by the caller. How do I communicate that the callee expects the IEqualityComparer<string> object held by the dictionary to perform, for example, a case-insensitive ordinal comparison?

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  • Pointers and Addresses in C

    - by Mohit
    #include "stdio.h" main() { int i=3,*x; float j=1.5,*y; char k='c',*z; x=&i; y=&j; z=&k; printf("\nAddress of x= %u",x); printf("\nAddress of y= %u",y); printf("\nAddress of z= %u",z); x++; y++;y++;y++;y++; z++; printf("\nNew Address of x= %u",x); printf("\nNew Address of y= %u",y); printf("\nNew Address of z= %u",z); printf("\nNew Value of i= %d",i); printf("\nNew Value of j= %f",j); printf("\nNew Value of k= %c\n",k); } Output: Address of x= 3219901868 Address of y= 3219901860 Address of z= 3219901875 New Address of x= 3219901872 New Address of y= 3219901876 New Address of z= 3219901876 New Value of i= 3 New Value of j= 1.500000 New Value of k= c The new address of variable y and z are same. How can two variables have same address and et have different values? Note: I used gcc compiler on Ubuntu 9.04

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  • Fitting Text into an Image

    - by Abs
    Hello all, I have a function which takes in a font (ttf or otf file) and generates an image of text in different fonts. The problem I have is trying to work out how I can make the text fit in the image regardless of the font-size, type of font, and amount of text. I have tried to make the image rectangle variable so that it contains the text of different fonts without cutting a bit of the text since the image is not long or wide enough. Here is the function that I currently have, I have tried using the number of characters to determine the width of the image, but in some cases for some fonts and sizes, it still gets cut off. function generate_image($save_path, $text, $font_path){ $length = strlen($text) * 15; // Create the image $im = imagecreatetruecolor($length, 40); $white = imagecolorallocate($im, 255, 255, 255); $grey = imagecolorallocate($im, 128, 128, 128); $black = imagecolorallocate($im, 0, 0, 0); imagefilledrectangle($im, 0, 0, $length, 40, $white); $font = $font_path; imagettftext($im, 30, 0, 0, 25, $black, $font, $text); if(imagepng($im, $save_path)){ $status = true; }else{ $status = false; } imagedestroy($im); return $status; } Thank you all for any help

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  • Join with Three Tables

    - by John
    Hello, In MySQL, I am using the following three tables (their fields are listed after their titles): comment: commentid loginid submissionid comment datecommented login: loginid username password email actcode disabled activated created points submission: submissionid loginid title url displayurl datesubmitted I would like to display "datecommented" and "comment" for a given "username," where "username" equals a variable called $profile. I would also like to make the "comment" a hyperlink to http://www...com/.../comments/index.php?submission='.$rowc["title"].'&submissionid='.$rowc["submissionid"].'&url='.$rowc["url"].'&countcomments='.$rowc["countComments"].'&submittor='.$rowc["username"].'&submissiondate='.$rowc["datesubmitted"].'&dispurl='.$rowc["displayurl"].' where countComments equals COUNT(c.commentid) and $rowc is part of the query listed below. I tried using the code below to do what I want, but it didn't work. How could I change it to make it do what I want? Thanks in advance, John $sqlStrc = "SELECT s.loginid ,s.title ,s.url ,s.displayurl ,s.datesubmitted ,l.username ,l.loginid ,s.title ,s.submissionid ,c.comment ,c.datecommented ,COUNT(c.commentid) countComments FROM submission s INNER JOIN login l ON s.loginid = l.loginid LEFT OUTER JOIN comment c ON c.loginid = l.loginid WHERE l.username = '$profile' GROUP BY c.loginid ORDER BY s.datecommented DESC LIMIT 10"; $resultc = mysql_query($sqlStrc); $arrc = array(); echo "<table class=\"samplesrec1c\">"; while ($rowc = mysql_fetch_array($resultc)) { $dtc = new DateTime($rowc["datecommented"], $tzFromc); $dtc->setTimezone($tzToc); echo '<tr>'; echo '<td class="sitename3c">'.$dtc->format('F j, Y &\nb\sp &\nb\sp g:i a').'</a></td>'; echo '<td class="sitename1c"><a href="http://www...com/.../comments/index.php?submission='.$rowc["title"].'&submissionid='.$rowc["submissionid"].'&url='.$rowc["url"].'&countcomments='.$rowc["countComments"].'&submittor='.$rowc["username"].'&submissiondate='.$rowc["datesubmitted"].'&dispurl='.$rowc["displayurl"].'">'.stripslashes($rowc["comment"]).'</a></td>'; echo '</tr>'; } echo "</table>";

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  • Circumvent c++ null-terminated string frustration

    - by ypnos
    I'm using boost::program_options and it suffers from the same as many other c++ libs, even std itself: It still uses C-style null-terminated strings, because nobody really likes the weak std::string. The method in question is: options_description_easy_init& operator()(const char* name, const value_semantic* s, const char* description); The typical use case is just fine: options.add_options() ("graphical", bool_switch(&isGraphical)->default_value(false), "Show any graphical output during runtime") However, I need the name of the option to be set dynamically. The reason is that in some cases I nead a custom prefix, which is added to the string by my function std::string key(const std::string& k): options.add_options() (key("graphical"), bool_switch(&isGraphical)->default_value(false), "Show any graphical output during runtime") This fails. I could now use c_str() on the std::string but that's evil -- I don't know how long program_options keeps the variable around and if my string is still alive when needed. I could also reserve memory in a buffer etc. and hand in that. The buffer is never freed and it sucks/is evil. Is there anything else I can do to circumvent the C-style string mess in this situation?

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  • optimize output value using a class and public member

    - by wiso
    Suppose you have a function, and you call it a lot of times, every time the function return a big object. I've optimized the problem using a functor that return void, and store the returning value in a public member: #include <vector> const int N = 100; std::vector<double> fun(const std::vector<double> & v, const int n) { std::vector<double> output = v; output[n] *= output[n]; return output; } class F { public: F() : output(N) {}; std::vector<double> output; void operator()(const std::vector<double> & v, const int n) { output = v; output[n] *= n; } }; int main() { std::vector<double> start(N,10.); std::vector<double> end(N); double a; // first solution for (unsigned long int i = 0; i != 10000000; ++i) a = fun(start, 2)[3]; // second solution F f; for (unsigned long int i = 0; i != 10000000; ++i) { f(start, 2); a = f.output[3]; } } Yes, I can use inline or optimize in an other way this problem, but here I want to stress on this problem: with the functor I declare and construct the output variable output only one time, using the function I do that every time it is called. The second solution is two time faster than the first with g++ -O1 or g++ -O2. What do you think about it, is it an ugly optimization?

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  • Calling arrays from other methods in a different class

    - by Jake H
    Hello, I need help dealing with an array in my java program. in my first class, "test", I set 4 variables and then send them to my other class (test2). arr[i] = new test2(id, fname, lname, case); at that point, variables are set and then I want to return those variables. So in the test2 class, I have a method that strictly returns one of those variables public int getId(){ return id; } I understand this is a little stupid, but professor gets what professor wants I guess. What I want to do now is in my main method in "test" I want to retrieve that variable and sort the array based on that int. Unfortunately, I have to create my own sort function, but I think this would work for what I want to do. for(j = 0; j < arr.length; j++){ int indexMin =j; for(i = j; i < arr.length;i++){ if(arr[i] < arr[indexMin]){ indexMin = i; } } int tmp = arr[j]; arr[j] = arr[indexMin]; arr[indexMin] = tmp; } I appreciate any help anyone could provide. Thank you

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  • How to Prevent PostBack Event Handler from Firing

    - by user331744
    I have a custom class (ServerSideValidator.vb) that validates user input on server side (it doesn't use any of the .NET built in validators, therefore Page.Validate() is not an option for me). I am calling the Validate() method on page.IsPostback event and the class performs without any problem My issue is, when validation fails (returns false), I want to stop the postback event handler from firing, but load the page along with all the controls and user-input values in them. If I do, Response.End(), the page comes up blank. I can programmatically instruct the page to go to the previous page (original form before postback), but it loses all user-inputs. I thought of creating a global boolean variable in the page code behind file and check the value before performing any postback method, but this approach takes away from my plan to provide all functionalities inside the class itself. The page object is being referenced to ServerSideValidator. Seems like all the postback related properties/variables I come across inside Page class are 'Readonly' and I can't assign value(s) to control/prevent postback event from firing. Any idiea on how I can accomplish this? Please let me know if you need further details

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  • PHP Object Access Syntax Question with the $

    - by ImperialLion
    I've been having trouble searching for this answer because I am not quite sure how to phrase it. I am new to PHP and still getting my feet on the ground. I was writing a page with a class in it that had the property name. When I originally wrote the page there was no class so I just had a variable called $name. When I went to encapsulate it in a class I accidental changed it to be $myClass->$name. It tool me a while to realize that the syntax I needed was $myClass->name. The reason it took so long was the error I kept getting was "Attempt to access a null property" or something along those lines. The error lead me to believe it was a data population error. My question is does $myClass->$name have a valid meaning? In other words is there a time you would use this and a reason why it doesn't create a syntax error? If so what is the semantic meaning of that code? When would I use it if it is valid? If its not valid, is there a reason that it doesn't create a syntax error?

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