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WPF performance for large number of elements on the screen

- by Mark

Im currently trying to create a Scene in WPF where I have around 250 controls on my screen and the user can Pan and Zoom in and out of these controls using the mouse. I have run the WPF Performance Suite tools on the application when there are a large number of these controls on the screen (i.e. when the user has zoomed right out) the FPS drops down to around 15 which is not very good. Here is the basic outline of the XAML: <Window> <Window.Resources> <ControlTemplate x:Key="LandTemplate" TargetType="{x:Type local:LandControl}"> <Canvas> <Path Fill="White" Stretch="Fill" Stroke="Black" StrokeThickness="1" Width="55.5" Height="74.687" Data="M0.5,0.5 L55,0.5 L55,74.187 L0.5,74.187 z"/> <Canvas x:Name="DetailLevelCanvas" Width="24.5" Height="21" Canvas.Left="15.306" Canvas.Top="23.972"> <TextBlock Width="21" Height="14" Text="712" TextWrapping="Wrap" Foreground="Black"/> <TextBlock Width="17.5" Height="7" Canvas.Left="7" Canvas.Top="14" Text="614m2" TextWrapping="Wrap" FontSize="5.333" Foreground="Black"/> </Canvas> </Canvas> </ControlTemplate> </Window.Resources> ... <local:LandControl Width="55.5" Height="74.552" Canvas.Top="xxx" Template=" {StaticResource LandTemplate}" RenderTransformOrigin="0.5,0.5" Canvas.Left="xxx"> <local:LandControl Width="55.5" Height="74.552" Canvas.Top="xxx" Template=" {StaticResource LandTemplate}" RenderTransformOrigin="0.5,0.5" Canvas.Left="xxx"> <local:LandControl Width="55.5" Height="74.552" Canvas.Top="xxx" Template=" {StaticResource LandTemplate}" RenderTransformOrigin="0.5,0.5" Canvas.Left="xxx"> <local:LandControl Width="55.5" Height="74.552" Canvas.Top="xxx" Template=" {StaticResource LandTemplate}" RenderTransformOrigin="0.5,0.5" Canvas.Left="xxx"> ... and so on... </Window> Ive tried to minimise the details in the control template and I even did a massive find and replace of the controls to just put their raw elements inline instead of using a template, but with no noticeable performance improvements. I have seen other SO questions about this and people say to do custom drawing, but I dont really see how that make sense when you have to zoom and pan like I do. If anyone can help out here, that would be great! Mark

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SWIG & Java Use of carrays.i and array_functions for C Array of Strings

- by c12

I have the below configuration where I'm trying to create a test C function that returns a pointer to an Array of Strings and then wrap that using SWIG's carrays.i and array_functions so that I can access the Array elements in Java. Uncertainties: %array_functions(char, SWIGArrayUtility); - not sure if char is correct inline char *getCharArray() - not sure if C function signature is correct String result = getCharArray(); - String return seems odd, but that's what is generated by SWIG SWIG.i: %module Test %{ #include "test.h" %} %include <carrays.i> %array_functions(char, SWIGArrayUtility); %include "test.h" %pragma(java) modulecode=%{ public static char[] getCharArrayImpl() { final int num = numFoo(); char ret[] = new char[num]; String result = getCharArray(); for (int i = 0; i < num; ++i) { ret[i] = SWIGArrayUtility_getitem(result, i); } return ret; } %} Inline Header C Function: #ifndef TEST_H #define TEST_H inline static unsigned short numFoo() { return 3; } inline char *getCharArray(){ static char* foo[3]; foo[0]="ABC"; foo[1]="5CDE"; foo[2]="EEE6"; return foo; } #endif Java Main Tester: public class TestMain { public static void main(String[] args) { System.loadLibrary("TestJni"); char[] test = Test.getCharArrayImpl(); System.out.println("length=" + test.length); for(int i=0; i < test.length; i++){ System.out.println(test[i]); } } } Java Main Tester Output: length=3 ? ? , SWIG Generated Java APIs: public class Test { public static String new_SWIGArrayUtility(int nelements) { return TestJNI.new_SWIGArrayUtility(nelements); } public static void delete_SWIGArrayUtility(String ary) { TestJNI.delete_SWIGArrayUtility(ary); } public static char SWIGArrayUtility_getitem(String ary, int index) { return TestJNI.SWIGArrayUtility_getitem(ary, index); } public static void SWIGArrayUtility_setitem(String ary, int index, char value) { TestJNI.SWIGArrayUtility_setitem(ary, index, value); } public static int numFoo() { return TestJNI.numFoo(); } public static String getCharArray() { return TestJNI.getCharArray(); } public static char[] getCharArrayImpl() { final int num = numFoo(); char ret[] = new char[num]; String result = getCharArray(); System.out.println("result=" + result); for (int i = 0; i < num; ++i) { ret[i] = SWIGArrayUtility_getitem(result, i); System.out.println("ret[" + i + "]=" + ret[i]); } return ret; } }

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Why no switch on pointers?

- by meeselet

For instance: #include <stdio.h> void why_cant_we_switch_him(void *ptr) { switch (ptr) { case NULL: printf("NULL!\n"); break; default: printf("%p!\n", ptr); break; } } int main(void) { void *foo = "toast"; why_cant_we_switch_him(foo); return 0; } gcc test.c -o test test.c: In function 'why_cant_we_switch_him': test.c:5: error: switch quantity not an integer test.c:6: error: pointers are not permitted as case values Just curious. Is this a technical limitation? EDIT People seem to think there is only one constant pointer expression. Is that is really true, though? For instance, here is a common paradigm in Objective-C (it is really only C aside from NSString, id and nil, which are merely a pointers, so it is still relevant — I just wanted to point out that there is, in fact, a common use for it, despite this being only a technical question): #include <stdio.h> #include <Foundation/Foundation.h> static NSString * const kMyConstantObject = @"Foo"; void why_cant_we_switch_him(id ptr) { switch (ptr) { case kMyConstantObject: // (Note that we are comparing pointers, not string values.) printf("We found him!\n"); break; case nil: printf("He appears to be nil (or NULL, whichever you prefer).\n"); break; default: printf("%p!\n", ptr); break; } } int main(void) { NSString *foo = @"toast"; why_cant_we_switch_him(foo); foo = kMyConstantObject; why_cant_we_switch_him(foo); return 0; } gcc test.c -o test -framework Foundation test.c: In function 'why_cant_we_switch_him': test.c:5: error: switch quantity not an integer test.c:6: error: pointers are not permitted as case values It appears that the reason is that switch only allows integral values (as the compiler warning said). So I suppose a better question would be to ask why this is the case? (though it is probably too late now.)

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Sanity Check: change event not firing first time using keyboard

- by macca1

I've done a good amount of research on this and found a bunch of reported problems and solutions but the general consensus seems that all change problems in IE6 were fixed in jQuery 1.4.2. I'm having an issue where a change event is not firing in jQuery 1.4.2, but it did fire successfully in jQuery 1.3.2. This is in IE6. I'm about to submit a bug for this, but for my sanity I wanted to post it here first to see if there's something dumb I'm missing. I don't understand why this is working this way... <HTML> <HEAD> <TITLE>jQuery 1.4.2 Problem </TITLE> <script src="jquery-1.4.2.min.js" type="text/javascript"></script> <script> $(document).ready( function() { $("#firstBox").change(function() { alert("CHANGE"); }); // ONLOAD of document autofocus into the first element... $("form").find(":input:visible:first").focus() }); </script> </HEAD> <BODY> <form> <select id="firstBox"> <option value="" selected="selected">--</option> <option value="1">One</option> <option value="2">Two</option> </select> <br><br> <input size="10" id="secondBox"> </form> </BODY> </HTML> Simple enough, right? Onload of the page, give the first element focus. Onchange of the first element, alert. If you use the mouse, it works as expected. The page loads, the focus is in the drop down, you change the option, you get the alert. The problem is if you use the keyboard. The page loads, the focus is in the drop down, you press the down arrow. The option changes. Tab off the field, no alert. Weird. To make it even weirder, if you tab back into the field and change it again (all using the keyboard), the change event DOES fire after tab out this time. Any ideas?

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Difficulty adding widgets to django form.

- by codingJoe

I have a django app that tracks activities that can benefit a classroom. Using the django examples, I was able to build a form to enter this data. But when I try to add widgets to that form, things get tricky. What I want is a calendar widget that lets the user enter the 'activity_date' field using a widget. If I use Admin interface. The AdminDateWidget works fine. however. This particular user isn't allowed access to the admin interface so I need a different way to present this widget. Also I couldn't figure out how to make the bring the admin widget over into non-admin pages. So I tried a custom widget. This is the first custom widget I've built, so I'm not quite sure what is supposed to be going on here. Any Expert Advice? How do I get my date widget to work? # The Model class Activity(models.Model): activity_date = models.DateField() activity_type = models.CharField(max_length=50, choices=ACTIVITY_TYPES) activity_description = models.CharField(max_length=200) activity_duration= models.DecimalField(decimal_places=2, max_digits=4) est_attendance = models.IntegerField("Estimated attendance") # The Form class ActivityForm(forms.ModelForm): # The following line causes lockup if enabled. # With the DateTimeWidget removed, the form functions correctly except that there is no widget. #activity_date = forms.DateField(label=_('Date'), widget=DateTimeWidget) ##!!! Point of Error !!! class Meta: model = Activity fields = ('activity_date', 'activity_type', 'activity_description', 'activity_duration', 'est_attendance') def __init__(self, *args, **kwargs): super(ActivityForm, self).__init__(*args, **kwargs) instance = getattr(self, 'instance', None) edit_aid = kwargs.get('edit_aid', False) # On a different approach, the following also didn't work. #self.fields['activity_date'].widget = widgets.AdminDateWidget() # The Widget # Example referenced: http://djangosnippets.org/snippets/391/ calbtn = u""" <button id="calendar-trigger">...</button> <img src="%s/site_media/images/icon_calendar.gif" alt="calendar" id="%s_btn" style="cursor: pointer; border: 1px solid #8888aa;" title="Select date and time" onmouseover="this.style.background='#444444';" onmouseout="this.style.background=''" /> <script type="text/javascript"> Calendar.setup({ trigger : "calendar-trigger", inputField : "%s" }); </script>""" class DateTimeWidget(forms.widgets.TextInput): dformat = '%Y-%m-%d %H:%M' def render(self, name, value, attrs=None): print "DTWgt render name=%s, value=%s" % name, value if value is None: value = '' final_attrs = self.build_attrs(attrs, type=self.input_type, name=name) if value != '': try: final_attrs['value'] = \ force_unicode(value.strftime(self.dformat)) except: final_attrs['value'] = \ force_unicode(value) if not final_attrs.has_key('id'): final_attrs['id'] = u'%s_id' % (name) id = final_attrs['id'] jsdformat = self.dformat #.replace('%', '%%') cal = calbtn % (settings.MEDIA_URL, id, id, jsdformat, id) a = u'<input%s />%s' % (forms.util.flatatt(final_attrs), cal) print "render return %s " % a return mark_safe(a) def value_from_datadict(self, data, files, name): print "DTWgt value_from_datadict" dtf = forms.fields.DEFAULT_DATETIME_INPUT_FORMATS empty_values = forms.fields.EMPTY_VALUES value = data.get(name, None) if value in empty_values: return None if isinstance(value, datetime.datetime): return value if isinstance(value, datetime.date): return datetime.datetime(value.year, value.month, value.day) for format in dtf: try: return datetime.datetime(*time.strptime(value, format)[:6]) except ValueError: continue return None

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Unique_ptr compiler errors

- by Godric Seer

I am designing and entity-component system for a project, and C++ memory management is giving me a few issues. I just want to make sure my design is legitimate. So to start I have an Entity class which stores a vector of Components: class Entity { private: std::vector<std::unique_ptr<Component> > components; public: Entity() { }; void AddComponent(Component* component) { this -> components.push_back(std::unique_ptr<Component>(component)); } ~Entity(); }; Which if I am not mistaken means that when the destructor is called (even the default, compiler created one), the destructor for the Entity, will call ~components, which will call ~std::unique_ptr for each element in the vector, and lead to the destruction of each Component, which is what I want. The component class has virtual methods, but the important part is its constructor: Component::Component(Entity parent) { parent.addComponent(this) // I am not sure if this would work like I expect // Other things here } As long as passing this to the method works, this also does what I want. My confusion is in the factory. What I want to do is something along the lines of: std::shared_ptr<Entity> createEntity() { std::shared_ptr<Entity> entityPtr(new Entity()); new Component(*parent); // Initialize more, and other types of Components return entityPtr; } Now, I believe that this setup will leave the ownership of the Component in the hands of its Parent Entity, which is what I want. First a small question, do I need to pass the entity into the Component constructor by reference or pointer or something? If I understand C++, it would pass by value, which means it gets copied, and the copied entity would die at the end of the constructor. The second, and main question is that code based on this sample will not compile. The complete error is too large to print here, however I think I know somewhat of what is going on. The compiler's error says I can't delete an incomplete type. My Component class has a purely virtual destructor with an implementation: inline Component::~Component() { }; at the end of the header. However since the whole point is that Component is actually an interface. I know from here that a complete type is required for unique_ptr destruction. The question is, how do I work around this? For reference I am using gcc 4.4.6.

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properies profile when writing word file

- by avani-nature

Hai frnds i am new to php i am having following problems in my coding... 1.Actually i am opening word document with com object and storing it in textarea. 2.when content gets opened in textarea i am editing that content and saving the document 3.actually when i edited that file and done save after that if i open word document then file properties-custom the old content getting removed i wannt to retain that even if i edited the word document..please do the needful i am using below code <?php $filename = 'C:/xampp/htdocs/mts/sites/default/files/a.doc'; //echo $filename; if(isset($_REQUEST['Save'])){ $somecontent = stripslashes($_POST['somecontent']); // Let's make sure the file exists and is writable first. if (is_writable($filename)) { // In our example we're opening $filename in append mode. // The file pointer is at the bottom of the file hence // that's where $somecontent will go when we fwrite() it. if (!$handle = fopen($filename, 'w')) { echo "Cannot open file ($filename)"; exit; } // Write $somecontent to our opened fi<form action="" method="get"></form>le. if (fwrite($handle, $somecontent) === FALSE) { echo "Cannot write to file ($filename)"; exit; } echo "Success, wrote ($somecontent) to file ($filename) <a href=".$_SERVER['PHP_SELF']."> - Continue - "; fclose($handle); } else { echo "The file $filename is not writable"; } } else{ // get contents of a file into a string $handle = fopen($filename, "r"); $somecontent = fread($handle, filesize($filename)); $word = new COM("word.application") or die ("Could not initialise MS Word object."); $word->Documents->Open(realpath("$filename")); // Extract content. $somecontent = (string) $word->ActiveDocument->Content; //echo $somecontent; $word->ActiveDocument->Close(false); $word->Quit(); $word = null; unset($word); fclose($handle); } ?> <h6>Edit file --------><? $filenam=explode("/",$filename);$filename=$filename[7]; echo $filename ;?></h6> <form name="form1" method="post" action=""> <p> <textarea name="somecontent" cols="100" rows="20"><? echo $somecontent ;?></textarea> </p> <div style='padding-left:250px;'><input type="submit" name="Save" value="Save"></div> </p> </form> <? } ?>

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Who calls the Destructor of the class when operator delete is used in multiple inheritance.

- by dicaprio-leonard

This question may sound too silly, however , I don't find concrete answer any where else. With little knowledge on how late binding works and virtual keyword used in inheritance. As in the code sample, when in case of inheritance where a base class pointer pointing to a derived class object created on heap and delete operator is used to deallocate the memory , the destructor of the of the derived and base will be called in order only when the base destructor is declared virtual function. Now my question is : 1) When the destructor of base is not virtual, why the problem of not calling derived dtor occur only when in case of using "delete" operator , why not in the case given below: derived drvd; base *bPtr; bPtr = &drvd; //DTOR called in proper order when goes out of scope. 2) When "delete" operator is used, who is reponsible to call the destructor of the class? The operator delete will have an implementation to call the DTOR ? or complier writes some extra stuff ? If the operator has the implementation then how does it looks like , [I need sample code how this would have been implemented]. 3) If virtual keyword is used in this example, how does operator delete now know which DTOR to call? Fundamentaly i want to know who calls the dtor of the class when delete is used. Sample Code class base { public: base() { cout<<"Base CTOR called"<<endl; } virtual ~base() { cout<<"Base DTOR called"<<endl; } }; class derived:public base { public: derived() { cout<<"Derived CTOR called"<<endl; } ~derived() { cout<<"Derived DTOR called"<<endl; } }; I'm not sure if this is a duplicate, I couldn't find in search. int main() { base *bPtr = new derived(); delete bPtr;// only when you explicitly try to delete an object return 0; }

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Why are these styles not visible in IE6

- by Laramie

Given the following markup <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML Strict//EN"><META http-equiv="Content-Type" content="text/html; charset=utf-8"> <HTML xmlns="http://www.w3.org/1999/xhtml"> <head> <style type="text/css"> div.apartBox { padding:12px; background: #FFFFFF; border: solid 1px #6182A3; } .browser { background: #fff; border: solid 1px #0055E3; border-top: solid 12px #0055E3; border-bottom: solid 4px #7A99C5; padding:10px 10px 8px 14px; color: #333; font: 0.8em/1 arial; margin: 8px 20px; } .callout { background: #EEF2F0; border: solid 1px #9CC7C0; padding:8px; } </style> </head> <BODY> <div class="apartBox" id="subPopout" style="Z-INDEX: 2; WIDTH: 400px; POSITION: relative"> <div id="upSubPop"> <div class="callout" id="subDetails"> <div class="browser"> <span id="txtExample">Me afecta que digan que soy incapaz.</span> </div> </div> </div> </div> </BODY></HTML> The styles from the css .browser and .callout are not visible in IE6 unless I manually remove the position:relative style from subPopout. This div is generated automatically from a modal popup so I unfortunately can't touch this style. It displays fine in FF. If I select the .browser div with my mouse, it displays when I unselect it!

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Error in Print Function in Bubble Sort MIPS?

- by m00nbeam360

Sorry that this is such a long block of code, but do you see any obvious syntax errors in this? I feel like the problem is that the code isn't printing correctly since the sort and swap methods were from my textbook. Please help if you can! .data save: .word 1,2,4,2,5,6 size: .word 6 .text swap: sll $t1, $a1, 2 #shift bits by 2 add $t1, $a1, $t1 #set $t1 address to v[k] lw $t0, 0($t1) #load v[k] into t1 lw $t2, 4($t1) #load v[k+1] into t1 sw $t2, 0($t1) #swap addresses sw $t0, 4($t1) #swap addresses jr $ra #return sort: addi $sp, $sp, -20 #make enough room on the stack for five registers sw $ra, 16($sp) #save the return address on the stack sw $s3, 12($sp) #save $s3 on the stack sw $s2, 8($sp) #save Ss2 on the stack sw $s1, 4($sp) #save $s1 on the stack sw $s0, 0($sp) #save $s0 on the stack move $s2, $a0 #copy the parameter $a0 into $s2 (save $a0) move $s3, $a1 #copy the parameter $a1 into $s3 (save $a1) move $s0, $zero #start of for loop, i = 0 for1tst: slt $t0, $s0, $s3 #$t0 = 0 if $s0 S $s3 (i S n) beq $t0, $zero, exit1 #go to exit1 if $s0 S $s3 (i S n) addi $s1, $s0, -1 #j - i - 1 for2tst: slti $t0, $s1, 0 #$t0 = 1 if $s1 < 0 (j < 0) bne $t0, $zero, exit2 #$t0 = 1 if $s1 < 0 (j < 0) sll $t1, $s1, 2 #$t1 = j * 4 (shift by 2 bits) add $t2, $s2, $t1 #$t2 = v + (j*4) lw $t3, 0($t2) #$t3 = v[j] lw $t4, 4($t2) #$t4 = v[j+1] slt $t0, $t4, $t3 #$t0 = 0 if $t4 S $t3 beq $t0, $zero, exit2 #go to exit2 if $t4 S $t3 move $a0, $s2 #1st parameter of swap is v(old $a0) move $a1, $s1 #2nd parameter of swap is j jal swap #swap addi $s1, $s1, -1 j for2tst #jump to test of inner loop j print exit2: addi $s0, $s0, 1 #i = i + 1 j for1tst #jump to test of outer loop exit1: lw $s0, 0($sp) #restore $s0 from stack lw $s1, 4($sp) #resture $s1 from stack lw $s2, 8($sp) #restore $s2 from stack lw $s3, 12($sp) #restore $s3 from stack lw $ra, 16($sp) #restore $ra from stack addi $sp, $sp, 20 #restore stack pointer jr $ra #return to calling routine .data space:.asciiz " " # space to insert between numbers head: .asciiz "The sorted numbers are:\n" .text print:add $t0, $zero, $a0 # starting address of array add $t1, $zero, $a1 # initialize loop counter to array size la $a0, head # load address of print heading li $v0, 4 # specify Print String service syscall # print heading out: lw $a0, 0($t0) # load fibonacci number for syscall li $v0, 1 # specify Print Integer service syscall # print fibonacci number la $a0, space # load address of spacer for syscall li $v0, 4 # specify Print String service syscall # output string addi $t0, $t0, 4 # increment address addi $t1, $t1, -1 # decrement loop counter bgtz $t1, out # repeat if not finished jr $ra # return

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Using boost::iterator

- by Neil G

I wrote a sparse vector class (see #1, #2.) I would like to provide two kinds of iterators: The first set, the regular iterators, can point any element, whether set or unset. If they are read from, they return either the set value or value_type(), if they are written to, they create the element and return the lvalue reference. Thus, they are: Random Access Traversal Iterator and Readable and Writable Iterator The second set, the sparse iterators, iterate over only the set elements. Since they don't need to lazily create elements that are written to, they are: Random Access Traversal Iterator and Readable and Writable and Lvalue Iterator I also need const versions of both, which are not writable. I can fill in the blanks, but not sure how to use boost::iterator_adaptor to start out. Here's what I have so far: template<typename T> class sparse_vector { public: typedef size_t size_type; typedef T value_type; private: typedef T& true_reference; typedef const T* const_pointer; typedef sparse_vector<T> self_type; struct ElementType { ElementType(size_type i, T const& t): index(i), value(t) {} ElementType(size_type i, T&& t): index(i), value(t) {} ElementType(size_type i): index(i) {} ElementType(ElementType const&) = default; size_type index; value_type value; }; typedef vector<ElementType> array_type; public: typedef T* pointer; typedef T& reference; typedef const T& const_reference; private: size_type size_; mutable typename array_type::size_type sorted_filled_; mutable array_type data_; // lots of code for various algorithms... public: class sparse_iterator : public boost::iterator_adaptor< sparse_iterator // Derived , array_type::iterator // Base (the internal array) (this paramater does not compile! -- says expected a type, got 'std::vector::iterator'???) , boost::use_default // Value , boost::random_access_traversal_tag? // CategoryOrTraversal > class iterator_proxy { ??? }; class iterator : public boost::iterator_facade< iterator // Derived , ????? // Base , ????? // Value , boost::?????? // CategoryOrTraversal > { }; };

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CSS Rollovers: how to main "hit area" size when hidden image is larger than anchor area

- by nukefusion

I have a small problem and I don't think what I want to do can be achieved with just pure CSS, but I figured I'd ask anyway. Basically, I have one DIV which contains a hyperlinked element that is smaller in size to it's parent DIV. So in effect I have a square within a square with the inner square being the "hit area". When I mouse over this inner square I want the background of the outer square to change. I know it's not possible to change the parent DIV's background on a:hover, but I figured I could give the illusion of it happening by nesting a hidden image inside the anchor. This works great until I want to "roll off". The problem is that I want the image to disappear when I leave the area of the anchor tag, not the larger hidden image. Is this possible? For the benefit of everyone I've provided an example to demonstrate what I mean: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta content="text/html; charset=utf-8" http-equiv="Content-Type" /> <title>Test Rollover</title> <link href="main.css" rel="stylesheet" type="text/css" /> </head> <body> <div id="d1"> <a href="#nogo"> <b id="b1"></b> <b id="b2"></b> </a> </div> </body> And the css: #b1 { width: 200px; height: 200px; top: 100px; left: 100px; background-color:aqua; position: absolute; } #b2 { width: 400px; height: 400px; background-color:lime; position: absolute; display: none; } #d1 { width: 400px; height: 400px; background-color:fuchsia; position: relative; } #d1 a:hover #b2 { display: block; } In this example I want the green outer square to disappear when I leave the bounds of the hidden inner blue square.

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How can I get jquery to toggle-fade a flashcard div open and closed on click?

- by Edward Tanguay

What do I have to change to the code below in order for the user to click on a flashcard header to open and close the flashcard answer? I couldn't get toggle() to work with fadein/fadeout the version below doesn't respond to the click code: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <script type="text/javascript" src="http://www.google.com/jsapi"></script> <script type="text/javascript"> google.load("jquery", "1.4.1"); google.setOnLoadCallback(function() { $("div > div.question").click(function() { if($(this).next().is(":hidden") { $(this).next().fadeIn("slow"); } else { $(this).next().fadeOut("slow"); } }); }); </script> <style> div.flashcard { margin: 0 10px 10px 0; } div.flashcard div.question { background-color:#ddd; width: 400px; padding: 5px; cursor: hand; cursor: pointer; } div.flashcard div.answer { background-color:#eee; width: 400px; padding: 5px; display: none; } </style> </head> <body> <div id="1" class="flashcard"> <div class="question">Who was Wagner?</div> <div class="answer">German composer, conductor, theatre director and essayist, primarily known for his operas (or "music dramas", as they were later called). Unlike most other opera composers, Wagner wrote both the music and libretto for every one of his works.</div> </div> <div id="2" class="flashcard"> <div class="question">Who was Thalberg?</div> <div class="answer">a composer and one of the most distinguished virtuoso pianists of the 19th century.</div> </div> </body> </html>

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How can I have a Makefile automatically rebuild source files that include a modified header file? (I

- by Nicholas Flynt

I have the following makefile that I use to build a program (a kernel, actually) that I'm working on. Its from scratch and I'm learning about the process, so its not perfect, but I think its powerful enough at this point for my level of experience writing makefiles. AS = nasm CC = gcc LD = ld TARGET = core BUILD = build SOURCES = source INCLUDE = include ASM = assembly VPATH = $(SOURCES) CFLAGS = -Wall -O -fstrength-reduce -fomit-frame-pointer -finline-functions \ -nostdinc -fno-builtin -I $(INCLUDE) ASFLAGS = -f elf #CFILES = core.c consoleio.c system.c CFILES = $(foreach dir,$(SOURCES),$(notdir $(wildcard $(dir)/*.c))) SFILES = assembly/start.asm SOBJS = $(SFILES:.asm=.o) COBJS = $(CFILES:.c=.o) OBJS = $(SOBJS) $(COBJS) build : $(TARGET).img $(TARGET).img : $(TARGET).elf c:/python26/python.exe concat.py stage1 stage2 pad.bin core.elf floppy.img $(TARGET).elf : $(OBJS) $(LD) -T link.ld -o $@ $^ $(SOBJS) : $(SFILES) $(AS) $(ASFLAGS) $< -o $@ %.o: %.c @echo Compiling $<... $(CC) $(CFLAGS) -c -o $@ $< #Clean Script - Should clear out all .o files everywhere and all that. clean: -del *.img -del *.o -del assembly\*.o -del core.elf My main issue with this makefile is that when I modify a header file that one or more C files include, the C files aren't rebuilt. I can fix this quite easily by having all of my header files be dependencies for all of my C files, but that would effectively cause a complete rebuild of the project any time I changed/added a header file, which would not be very graceful. What I want is for only the C files that include the header file I change to be rebuilt, and for the entire project to be linked again. I can do the linking by causing all header files to be dependencies of the target, but I cannot figure out how to make the C files be invalidated when their included header files are newer. I've heard that GCC has some commands to make this possible (so the makefile can somehow figure out which files need to be rebuilt) but I can't for the life of me find an actual implementation example to look at. Can someone post a solution that will enable this behavior in a makefile? EDIT: I should clarify, I'm familiar with the concept of putting the individual targets in and having each target.o require the header files. That requires me to be editing the makefile every time I include a header file somewhere, which is a bit of a pain. I'm looking for a solution that can derive the header file dependencies on its own, which I'm fairly certain I've seen in other projects.

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Idiomatic use of auto_ptr to transfer ownership to a container

- by heycam

I'm refreshing my C++ knowledge after not having used it in anger for a number of years. In writing some code to implement some data structure for practice, I wanted to make sure that my code was exception safe. So I've tried to use std::auto_ptrs in what I think is an appropriate way. Simplifying somewhat, this is what I have: class Tree { public: ~Tree() { /* delete all Node*s in the tree */ } void insert(const string& to_insert); ... private: struct Node { ... vector<Node*> m_children; }; Node* m_root; }; template<T> void push_back(vector<T*>& v, auto_ptr<T> x) { v.push_back(x.get()); x.release(); } void Tree::insert(const string& to_insert) { Node* n = ...; // find where to insert the new node ... push_back(n->m_children, auto_ptr<Node>(new Node(to_insert)); ... } So I'm wrapping the function that would put the pointer into the container, vector::push_back, and relying on the by-value auto_ptr argument to ensure that the Node* is deleted if the vector resize fails. Is this an idiomatic use of auto_ptr to save a bit of boilerplate in my Tree::insert? Any improvements you can suggest? Otherwise I'd have to have something like: Node* n = ...; // find where to insert the new node auto_ptr<Node> new_node(new Node(to_insert)); n->m_children.push_back(new_node.get()); new_node.release(); which kind of clutters up what would have been a single line of code if I wasn't worrying about exception safety and a memory leak. (Actually I was wondering if I could post my whole code sample (about 300 lines) and ask people to critique it for idiomatic C++ usage in general, but I'm not sure whether that kind of question is appropriate on stackoverflow.)

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Cleaning up a dynamic array of Objects in C++

- by Dr. Monkey

I'm a bit confused about handling an array of objects in C++, as I can't seem to find information about how they are passed around (reference or value) and how they are stored in an array. I would expect an array of objects to be an array of pointers to that object type, but I haven't found this written anywhere. Would they be pointers, or would the objects themselves be laid out in memory in an array? In the example below, a custom class myClass holds a string (would this make it of variable size, or does the string object hold a pointer to a string and therefore take up a consistent amount of space. I try to create a dynamic array of myClass objects within a myContainer. In the myContainer.addObject() method I attempt to make a bigger array, copy all the objects into it along with a new object, then delete the old one. I'm not at all confident that I'm cleaning up my memory properly with my destructors - what improvements could I make in this area? class myClass { private string myName; public unsigned short myAmount; myClass(string name, unsigned short amount) { myName = name; myAmount = amount; } //Do I need a destructor here? I don't think so because I don't do any // dynamic memory allocation within this class } class myContainer { int numObjects; myClass * myObjects; myContainer() { numObjects = 0; } ~myContainer() { //Is this sufficient? //Or do I need to iterate through myObjects and delete each // individually? delete [] myObjects; } void addObject(string name, unsigned short amount) { myClass newObject = new myClass(name, amount); myClass * tempObjects; tempObjects = new myClass[numObjects+1]; for (int i=0; i<numObjects; i++) tempObjects[i] = myObjects[i]); tempObjects[numObjects] = newObject; numObjects++; delete newObject; //Will this delete all my objects? I think it won't. //I'm just trying to delete the old array, and have the new array hold // all the objects plus the new object. delete [] myObjects; myObjects = tempObjects; } }

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dynamic button in jsp

- by kawtousse

hi everyone, in my jsp i have a table constructed dynamically like the following: retour.append("<tr>"); try { s= HibernateUtil.currentSession(); tx=s.beginTransaction(); Query query = s.createQuery(HQL_QUERY); for(Iterator it=query.iterate();it.hasNext();) { if(it.hasNext()){ Dailytimesheet object=(Dailytimesheet)it.next(); retour.append("<td>" +object.getActivity() +"</td>"); retour.append("<td>" +object.getProjectCode() + "</td>"); retour.append("<td>" +object.getWAName() + "</td>"); retour.append("<td>" +object.getTaskCode() +"</td>"); retour.append("<td>" +object.getTimeFrom() +"</td>"); retour.append("<td>" +object.getTimeSpent() + "</td>"); retour.append("<td>" +object.getPercentTaskComplete() + "</td>"); if (droitdaccess) { retour.append(""); retour.append(""); retour.append(""); retour.append("<td bordercolor=#FFFFFF>"); retour.append("<input type=\"hidden\" id=\"id_"+nomTab+"_"+compteur+"\" value=\""+object.getIdDailyTimeSheet()+"\"/>"); retour.append("<img src=\"icon_delete.gif\" onClick=\"deletearowById('id_"+nomTab+"_"+compteur+"')\" style=\"cursor:pointer\" name=\"action\" value=\"deleting\" />"); retour.append("</td>"); } } compteur++; retour.append("</tr>"); } //terminer la table. retour.append ("</table>"); next to the table i want to display a button named send in order to send the table content. I do not really want to dispaly this button where the table is empty. So at least if the table is populated by nly one record i want that button being displayed. How should i deal in this case. Thanks.

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System.MissingMemberException was unhandled by user code

- by AmRoSH

I'm using this code: Dim VehiclesTable1 = dsVehicleList.Tables(0) Dim VT1 = (From d In VehiclesTable1.AsEnumerable _ Select VehicleTypeName = d.Item("VehicleTypeName") _ , VTypeID = d.Item("VTypeID") _ , ImageURL = d.Item("ImageURL") _ , DailyRate = d.Item("DailyRate") _ , RateID = d.Item("RateID")).Distinct its linq to dataset and I Take Data on THis Rotator: <telerik:RadRotator ID="RadRotatorVehicleType" runat="server" Width="620px" Height="145" ItemWidth="155" ItemHeight="145" ScrollDirection="Left" FrameDuration="1" RotatorType="Buttons"> <ItemTemplate> <div style="text-align: center; cursor: pointer; width: 150px"> <asp:Image ID="ImageVehicleType" runat="server" Width="150" ImageUrl='<%# Container.DataItem("ImageURL") %>' /> <asp:Label ID="lblVehicleType" runat="server" Text='<%# Container.DataItem("VehicleTypeName") %>' Font-Bold="true"></asp:Label> <br /> <asp:Label ID="lblDailyRate" runat="server" Text='<%# Container.DataItem("DailyRate") %>' Visible="False"></asp:Label> <input id="HiddenVehicleTypeID" type="hidden" value='<%# Container.DataItem("VTypeID") %>' name="HiddenVehicleTypeID" runat="server" /> <input id="HiddenRateID" type="hidden" value='<%# Container.DataItem("RateID") %>' name="HiddenRateID" runat="server" /> </div> </ItemTemplate> <ControlButtons LeftButtonID="img_left" RightButtonID="img_right" /> </telerik:RadRotator> and I got this Exception: No default member found for type 'VB$AnonymousType_0(Of Object,Object,Object,Object,Object)'. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.MissingMemberException: No default member found for type 'VB$AnonymousType_0(Of Object,Object,Object,Object,Object)'. I don't know whats up ? Any help please. Thanks for who tried to solve this but I got solution: using '<%# DataBinder.Eval(Container.DataItem,"ImageURL") %>' instead of '<%# Container.DataItem("RateID") %>' Thanks,

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JavaFX - question regarding binding button's disabled state

- by jamiebarrow

I'm trying to create a dummy application that maintains a list of tasks. For now, all I'm trying to do is add to the list. I enter a task name in a text box, click on the add task button, and expect the list to be updated with the new item and the task name input to be cleared. I only want to be able to add tasks if the task name is not empty. The below code is my implementation, but I have a question regarding the binding. I'm binding the textbox's text variable to a string in my view model, and the button's disable variable to a boolean in my view model. I have a trigger to update the disabled state when the task name changes. When the binding of the task name happens the boolean is updated accordingly, but the button still appears disabled. But then when I mouse over the button, it becomes enabled. I believe this is due to JavaFX 1.3's binding being lazy - only updates the bound variable when it is read. Also, when I've added the task, I clear the task name in the model, but the textbox's text doesn't change - even though I'm using bind with inverse. Is there a way to make the textbox's text and the button's disabled state update automatically via the binding as I was expecting? Thanks, James AddTaskViewModel.fx: package jamiebarrow; import java.lang.System; public class AddTaskViewModel { function logChange(prop:String,oldValue,newValue):Void { println("{System.currentTimeMillis()} : {prop} [{oldValue}] to [{newValue}] "); } public var newTaskName: String on replace old { logChange("newTaskName",old,newTaskName); isAddTaskDisabled = (newTaskName == null or newTaskName.trim().length() == 0); }; public var isAddTaskDisabled: Boolean on replace old { logChange("isAddTaskDisabled",old,isAddTaskDisabled); }; public var taskItems = [] on replace old { logChange("taskItems",old,taskItems); }; public function addTask() { insert newTaskName into taskItems; newTaskName = ""; } } Main.fx: package jamiebarrow; import javafx.scene.control.Button; import javafx.scene.control.TextBox; import javafx.scene.control.ListView; import javafx.scene.Scene; import javafx.scene.layout.VBox; import javafx.stage.Stage; import javafx.scene.layout.HBox; def viewModel = AddTaskViewModel{}; var txtName: TextBox = TextBox { text: bind viewModel.newTaskName with inverse onKeyTyped: onKeyTyped }; function onKeyTyped(event): Void { txtName.commit(); // ensures model is updated cmdAddTask.disable = viewModel.isAddTaskDisabled;// the binding only occurs lazily, so this is needed } var cmdAddTask = Button { text: "Add" disable: bind viewModel.isAddTaskDisabled with inverse action: onAddTask }; function onAddTask(): Void { viewModel.addTask(); } var lstTasks = ListView { items: bind viewModel.taskItems with inverse }; Stage { scene: Scene { content: [ VBox { content: [ HBox { content: [ txtName, cmdAddTask ] }, lstTasks ] } ] } }

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show-hide image onmouseover

- by butters

I have 3 images on top of each other. The first one is a normal .jpg image, the second a greyscale version and the 3rd is some kind of effect i add with a transparent .png Now what i want is that, if i move the mouse over those images, the greyscale image is hidden or replaced by another image and afterwards visible again. The problem here is that i am a js noob, so it's kind of hard for me to find a solution ^^ my code looks something like this: <html> <head> <style type="text/css">  </style> </head> <body> <ul> <li> <div class="frame"> <div class="image"><img src="images/pic1.jpg" height="100" width="100"></div> <div class="greyscale"><img src="images/grey1.jpg" height="100" width="100"></div> <div class="effect">qwert</div> </div> </li> <li> <div class="frame"> <div class="image"><img src="images/pic2.jpg" height="100" width="100"></div> <div class="greyscale"><img src="images/grey2.jpg" height="100" width="100"></div> <div class="effect">qewrt</div> </div> </li> </ul> </body> </html> </code></pre> would be super-awesome if someone can help me out :)

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Good style for handling constructor failure of critical object

- by mtlphil

I'm trying to decide between two ways of instantiating an object & handling any constructor exceptions for an object that is critical to my program, i.e. if construction fails the program can't continue. I have a class SimpleMIDIOut that wraps basic Win32 MIDI functions. It will open a MIDI device in the constructor and close it in the destructor. It will throw an exception inherited from std::exception in the constructor if the MIDI device cannot be opened. Which of the following ways of catching constructor exceptions for this object would be more in line with C++ best practices Method 1 - Stack allocated object, only in scope inside try block #include <iostream> #include "simplemidiout.h" int main() { try { SimpleMIDIOut myOut; //constructor will throw if MIDI device cannot be opened myOut.PlayNote(60,100); //..... //myOut goes out of scope outside this block //so basically the whole program has to be inside //this block. //On the plus side, it's on the stack so //destructor that handles object cleanup //is called automatically, more inline with RAII idiom? } catch(const std::exception& e) { std::cout << e.what() << std::endl; std::cin.ignore(); return 1; } std::cin.ignore(); return 0; } Method 2 - Pointer to object, heap allocated, nicer structured code? #include <iostream> #include "simplemidiout.h" int main() { SimpleMIDIOut *myOut; try { myOut = new SimpleMIDIOut(); } catch(const std::exception& e) { std::cout << e.what() << std::endl; delete myOut; return 1; } myOut->PlayNote(60,100); std::cin.ignore(); delete myOut; return 0; } I like the look of the code in Method 2 better, don't have to jam my whole program into a try block, but Method 1 creates the object on the stack so C++ manages the object's life time, which is more in tune with RAII philosophy isn't it? I'm still a novice at this so any feedback on the above is much appreciated. If there's an even better way to check for/handle constructor failure in a siatuation like this please let me know.

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sorting a doubly linked list with merge sort.

- by user329820

Hi I have found this code in the internet and it was for arrays ,I want to change it for doubly linked list(instead of index we should use pointer) would you please help me that how can i change merge method(I have changed sort method by myself) also this is not my home work ,I love working with linked list!! public class MergeSort { private DoublyLinkedList LocalDoublyLinkedList; public MergeSort(DoublyLinkedList list) { LocalDoublyLinkedList = list; } public void sort() { if (LocalDoublyLinkedList.size() <= 1) { return; } DoublyLinkedList listOne = new DoublyLinkedList(); DoublyLinkedList listTwo = new DoublyLinkedList(); for (int x = 0; x < (LocalDoublyLinkedList.size() / 2); x++) { listOne.add(x, LocalDoublyLinkedList.getValue(x)); } for (int x = (LocalDoublyLinkedList.size() / 2) + 1; x < LocalDoublyLinkedList.size`(); x++) {` listTwo.add(x, LocalDoublyLinkedList.getValue(x)); } //Split the DoublyLinkedList again MergeSort sort1 = new MergeSort(listOne); MergeSort sort2 = new MergeSort(listTwo); sort1.sort(); sort2.sort(); merge(listOne, listTwo); } private void merge(DoublyLinkedList a, DoublyLinkedList b) { int x = 0; int y = 0; int z = 0; while (x < first.length && y < second.length) { if (first[x] < second[y]) { a[z] = first[x]; x++; } else { a[z] = second[y]; y++; } z++; } //copy remaining elements to the tail of a[]; for (int i = x; i < first.length; i++) { a[z] = first[i]; z++; } for (int i = y; i < second.length; i++) { a[z] = second[i]; z++; } } }

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How do I debug a difficult-to-reproduce crash with no useful call stack?

- by David M

I am encountering an odd crash in our software and I'm having a lot of trouble debugging it, and so I am seeking SO's advice on how to tackle it. The crash is an access violation reading a NULL pointer: First chance exception at $00CF0041. Exception class $C0000005 with message 'access violation at 0x00cf0041: read of address 0x00000000'. It only happens 'sometimes' - I haven't managed to figure out any rhyme or reason, yet, for when - and only in the main thread. When it occurs, the call stack contains one incorrect entry: For the main thread, which this is, it should show a large stack full of other items. At this point, all other threads are inactive (mostly sitting in WaitForSingleObject or a similar function.) I have only seen this crash occur in the main thread. It always has the same call stack of one entry, in the same method at the same address. This method may or may not be related - we do use the VCL in our application. My bet, though, is that something (possibly quite a while ago) is corrupting the stack, and the address where it's crashing is effectively random. Note it has been the same address across several builds, though - it's probably not truly random. Here is what I've tried: Trying to reproduce it reliably at a certain point. I have found nothing that reproduces it every time, and a couple of things that occasionally do, or do not, for no apparent reason. These are not 'narrow' enough actions to narrow it down to a particular section of code. It may be timing related, but at the point the IDE breaks in, other threads are usually doing nothing. I can't rule out a threading problem, but think it's unlikely. Building with extra debugging statements (extra debug info, extra asserts, etc.) After doing so, the crash never occurs. Building with Codeguard enabled. After doing so, the crash never occurs and Codeguard shows no errors. My questions: 1. How do I find what code caused the crash? How do I do the equivalent of walking back up the stack? 2. What general advice do you have for how to trace the cause of this crash? I am using Embarcadero RAD Studio 2010 (the project mostly contains C++ Builder code and small amounts of Delphi.)

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union marshalling issue in C#

- by senthil

I have union inside structure and the structure looks like struct tDeviceProperty { DWORD Tag; DWORD Size; union _DP value; }; typedef union _DP { short int i; LONG l; ULONG ul; float flt; double dbl; BOOL b; double at; FILETIME ft; LPSTR lpszA; LPWSTR lpszW; LARGE_INTEGER li; struct tBinary bin; BYTE reserved[40]; } __UDP; struct tBinary { ULONG size; BYTE * bin; }; from the tBinary structure bin has to be converted to tImage (structure is given below) struct tImage { DWORD x; DWORD y; DWORD z; DWORD Resolution; DWORD type; DWORD ID; diccid_t SourceID; const void *buffer; const char *Info; const char *UserImageID; }; to use the same in c# I have done marshaling but not giving proper values when converting the pointer to structure. The C# code is follows, tBinary tBin = new tBinary(); IntPtr tBinbuffer = Marshal.AllocCoTaskMem(Marshal.SizeOf(tBin)); Marshal.StructureToPtr(tBin.bin, tBinbuffer, false); tDeviceProperty tDevice = new tDeviceProperty(); tDevice.bin = tBinbuffer; IntPtr tDevicebuffer = Marshal.AllocCoTaskMem(Marshal.SizeOf(tDevice)); Marshal.StructureToPtr(tDevice.bin, tDevicebuffer, false); Battary tbatt = new Battary(); tbatt.value = tDevicebuffer; IntPtr tbattbuffer = Marshal.AllocCoTaskMem(Marshal.SizeOf(tbatt)); Marshal.StructureToPtr(tbatt.value, tbattbuffer, false); result = GetDeviceProperty(ref tbattbuffer); Battary v = (Battary)Marshal.PtrToStructure(tbattbuffer, typeof(Battary)); tDeviceProperty v2 = (tDeviceProperty)Marshal.PtrToStructure(tDevicebuffer, typeof(tDeviceProperty)); tBinary v3 = (tBinary)Marshal.PtrToStructure(tBinbuffer, typeof(tBinary));

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how can we make class with Linked list recursion ...

- by epsilon_G

Hi , I'm newbee in The C++ heaven and the OOP, ... I'd like to make some stuffs with the Data structures ... However,I'd like to merge two linked listes ... I made a class before "List" wich contain all what I need to programme something with List ... Add , Display .. The probleme is that I programmed the function "Merge2lists" which give us the third list .. How can I display the third list in the main program after using "Merge2lists" Plz , my prob with the Class and the OOP syntaxe ... try to give me the implementation in the main program ??? Otherwise,How can I apply function given pointer in main program wich declared in class .. Thankx class Liste { private: struct node { int elem ; node *next; }*p; public: LLC(); void Merge2lists (node* a, node * b,node *&result); ~LLC(); }; void List::Merge2lists (node* a, node * b,node *&result) { result = NULL; if (a==NULL) { result=b; return;} else if (b==NULL) { result=a; return;} if (a->elem <= b->elem) { result = a; Merge2lists(a->next, b,result->next); } else { result = b; Merge2lists(a, b->next,result->next); } return; } int main() { liste a ; a.Aff_Val(46); a.Aff_Val(54); a.add_as_first(2); a.add_as_first(1); a.Display(); /*This to displat the elemnts ... Don't care about it it's easy to make*/ list liste2; b.Add(2); b.Add(14); b.Add(16); list result; Merge2lists (a,b,result); /*The probleme is here , how can I use this in my program */

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