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• How to change the current selection in a wxListbook from another thread?

  - by George Edison

  How can I change the current selection in a wxListbook from another thread? When I pass the listbook's pointer to the thread and try to change the selection, the app crashes. What is a safe way of doing this? Is there some message I can send to it?

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• Is there any way to make gcc print offending lines when it emits an error?

  - by Alex

  I have a large codebase that I've been tasked with porting to 64 bits. The code compiles, but it prints a very large amount of incompatible pointer warnings (as is to be expected.) Is there any way I can have gcc print the line on which the error occurs? At this point I'm just using gcc's error messages to try to track down assumptions that need to be modified, and having to look up every one is not fun.

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• 'Invalid conversion from some_type** to const some_type**'

  - by petersohn

  I've got a function that requires const some_type** as an argument (some_type is a struct, and the function needs a pointer to an array of this type). I declared a local variable of type some_type*, and initialized it. Then I call the function as f(&some_array), and the compiler (gcc) says: error: invalid conversion from ‘some_type**’ to ‘const some_type**’ What's the problem here? Why can't I convert a variable to const?

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• Convert NSString to string

  - by coure06

  NSDate *now = [NSDate date]; NSDateFormatter *formatter = [[NSDateFormatter alloc] init]; [formatter setDateFormat:@"yyyy"]; NSString *stringFromDate = [formatter stringFromDate:now]; CGContextShowTextAtPoint(context, 50, 50, stringFromDate, 5); I am not getting the exact date? also getting warning while compiling warning: passing argument 4 of 'CGContextShowTextAtPoint' from incompatible pointer type

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• Are there pointers in php?

  - by donalg d

  What does this code mean? Is this how you declare a pointer in php? $this->entryId = $entryId;

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• What is the point of function pointers?

  - by gramm

  Hi, I have trouble seing the utility of the function pointers. I guess it may be useful in some cases (they exist, after all), but I can't think of a case where it's better or unavoidable to use a function pointer. Could you give some example of good use of function pointers (in C or C++)? Many thanks :)

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• How do I change the default sounds for the calendar warning function in CE 5.0?

  - by Joe M

  I have an old Moto Q that I would like to change the default alarm sound in the Calendar function. Right now, it seems to pick up the Alarm4.mid file in the Windows directory, which is embedded in ROM, so the filenames can't be changed. Is there a way to change the file pointer in the Calendar function to another file or is there another way to get around this?

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• STL map - insert or update

  - by CodeJunkie

  I have a map of objects and I want to update the object mapped to a key, or create a new object and insert into the map. The update is done by a different function that takes a pointer to the object (void update(MyClass *obj)) What is the best way to "insert or update" an element in a map?

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• Determining the word width in C

  - by das_weezul

  Hi! I'm learning C right now and so I'm fiddling about with pointers. Is there a way to determine the word width of the CPU in C because I'm writing a small program which prints it's own stack (Because I'm curious how it is structured), so that information would come in handy. Right now I'm using an int pointer, as an integer is 4 Bytes wide and I'm using a 32-bit Intel Atom CPU. Thanks in advance, C gurus ;o)

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• Linux signals with extra information parameter

  - by Tester

  I was to have some extra information in the callback to sa_sigaction handler, it does not seems possible. So I was wondering if you could suggest me alternatives. Basic requirements: Function A raises an signal/event with a pointer to a struct Handler function tackles the event. The handler function would only be called on an event and a loop to wait for the event, as in select() , is undesirable. TIA

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• What is the origin / meaning of these variable naming conventions?

  - by Andrew Hubbs

  What is the general meaning and where did it start to have variables with leading or trailing underscores? ex: _varName and varName_ I have always thought a leading underscore indicated the variable was a pointer but I don't know where I got this idea. Recently I have seen these naming conventions used in Java which makes that reasoning completely wrong.

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• C++ interview question involving class pointers

  - by benjamin button

  Lets say there is a base class pointer which is pointing to a base class object: baseclass *bptr; bptr= new baseclass; now if i do bptr= new derived; what is the problem here?

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• LInux C++: how do profile time wasted due to cache misses?

  - by anon

  I know that I can use gprof to benchmark my code. However, I have this problem -- I have a smart pointer that has an extra level of indirection (think of it as a proxy object). As a result, I have this extra layer that effects pretty much all functions, and screws with caching. Is there a way to measure the time my CPU wastes due to cache misses? Thanks!

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• Scan Numbers among letters in a Sentence

  - by ZaZu

  Hello, I have a pretty easy question. (using C) In a sentence such as In this document, there are 345 words and 6 figures How can I scan 345 and 6 while ignoring all that is in between ? I tried fscanf(FILE *pointer,"%d %d",&words,&figs); But it only gets the first value ... What am I doing wrong ?

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• C++ variable alias - what's that exactly, and why is it better to turn if off?

  - by Poni

  I've read the essay Surviving the Release Version. Under the "Aliasing bugs" clause it says: You can get tighter code if you tell the compiler that it can assume no aliasing.... I've also read Aliasing (computing). What exactly is a variable alias? I understand it means using a pointer to a variable is an alias, but, how/why does it affect badly, or in other words - why telling the compiler that it can assume no aliasing would get me a "tighter code"

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• managing IB objects without iboutlets

  - by palominoz

  i have got 24 buttons in my project.I need to manage them but I don't want to get my MainViewController polluted by 24 declarations of pointers, properties & synthesizes. i was thinking about using buttonPushed functions and do it like: -(IBAction)buttonPushed:(id)sender{ UIbutton *button=sender; [buttons addObjectAtIndex:[sender tag]]; } my question is:is sender a pointer to the IBObject?

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• unix DECLARE_WAIT_QUEUE_HEAD (var) var prototype?

  - by yoavstr

  hello i want to work with 2 queue in the module where i change my pointer to them therefore i need to use : //declartion wait_queue_head_t **currentQ; DECLARE_WAIT_QUEUE_HEAD (readWaitQ1); DECLARE_WAIT_QUEUE_HEAD (readWaitQ2); if(condition){ currentQ = &readWaitQ1; }else{ currentQ = &readWaitQ2; } but i get incorrect type for wake_up an other stuff using the queue. even thought i google it i couldnt find an answer can someone just give me the prototype needed?...

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• add a custom view/windows in the mac os X dock

  - by AP

  Hello, I would like to add a custom view (a pager) in the dock, just before the trash and was wondering on how to perform a such task. Do you have any pointer to help me to start? Thanks in advance for your help :) regards,

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• Sample code for POST + cookie?

  - by OverTheRainbow

  Hello, I've been googling for some VB.Net code to authenticate to a web server with the POST method, receive a session ID in a cookie, and then send this cookie along with all GET queries... but all I found is half-working code or C# code, ie. difficult to use for a VB.Net newbie. Would someone have some code handy or some pointer that I could use to get started? Thank you.

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• C++, is it possible to dimension array

  - by aaa

  hi. Suppose I have some pointer, which I want to reinterpret as static dimension array reference: double *p; double (&r)[4] = ?(p); // some construct? Is it possible to do so? how do I do it?

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• C++ interview question

  - by benjamin button

  as i am not an expert in c++,i was not aware of the answer to this question asked in one of the interviews. lets say there is a base class pointer which is pointing to a base class object: baseclass *bptr; bptr= new baseclass; now if i do bptr= new derived; what is the problem here?

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• what is the difference between DWORD and HANDLE type in C?

  - by moon

  i have a thread with return type DWORD in c but it is then handled by a HANDLE type pointer, what is difference between these two types?

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• problems with 'free' in C

  - by lego69

  hello, can somebody please explain can I free const char* ? I allocated new memory using malloc and when I'm trying to free it I always receive an error incompatible pointer type thanks in advance something like this char* name="Arnold"; const char* str=malloc(stlen(name)+1); free(str); <- here bug

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• c++, when do you need/have to pass data as (*&)

  - by ra170

  I came across people passing data objects as: declaration: DataObject * data = 0; calling it as: SomeMethod( data ); definition of Somethod: void SomeMethod(SomeObject * & object) My obvious question is, when and why do you have to do this (& *)? Is it passing the pointer as reference?

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• C++ Pass a hidden arg to a class constructor?

  - by JP

  I would like to define a class that accept the pointer to it's parent class as an Argument, but would it be possible to somehow pass it without needing to pass it directly such as: class Child { public: Child(Parent* hiddenArg); }; class Parent { public: Child myChild; }; I know this is weird, but I am making my own Signal/Slot implementation and Child would be a signal defined, but I would like to get the parent so I can use it's Event Dispatcher...

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