Hi all, Problem: I try to deallocate memory pointed by pointer items of an STL list. This should work fine but in my case, there can be duplicate pointers in the list and I get a double dealloc exception even though I test whether the pointer is NULL or not (see source code below). How can I solve this problem ? Environment: Debian...
I'm trying to use the standard library's qsort to sort an array of wide characters: wchar_t a = L'a'; wchar_t a1 = L'ä'; wchar_t b = L'z'; wchar_t chararray[] = {b, a, a1}; length = wcslen(chararray); qsort(chararray, length, sizeof(wchar_t), wcscoll); Now I think the functions involved have these prototypes: int wcscoll(const wch...
Possible Duplicate: Why cant I convert char* to a const char const* in C? I am curious, why can't I pass a char ** to const char ** function? Where as it is OK to pass char * to a const char * function it seems not to be OK to do it with double pointers. I thought it was always ok to add constness (but not ok to drop constness...
I'm developing a GUI library with a friend and we faced the problem of how to determine whether a certain element should be clickable or not (Or movable, or etc.). We decided to just check if a function exists for a specific object, all gui elements are stored in a vector with pointers to the base class. So for example if I have class...
class Foo { public: static const int kType = 42; }; void Func() { Foo *bar = NULL; int x = bar->kType; putc(x, stderr); } Is this defined behavior? I read through the C++ standard but couldn't find anything about accessing a static const value like this... I've examined the assembly produced by GCC 4.2, Clang++, and Visual Studio ...
I have a pointer in a struct. And I passed a struct pointer to this pointer. But I could not type cast back to this pointer to struct. public class Test { // Pointer ptr = new Memory(4); } public class Temp extends Structure { // } Test tst = new Test(); Temp tmp = new Temp(); tst.ptr = tmp.getPointer(); ... Temp...
The following code causes a SIGSEGV, but only while debugging. #include <stdio.h> #include <stdlib.h> typedef struct enemy_desc { int type; int x; int y; }enemy; int main() { enemy **enemies; enemies=(enemy **)malloc(sizeof(enemy *)*16); enemies[0]->type=23; printf("%i",enemies[0]->type); return 0; } ...
I have the following program. However, I can't understand why I have to pass the address of the array. When they are both pointing to the same address. Which is the address of the first element of the array of int's. I get a warning when I try and do this "assignment from incompatible pointer type": ptr = var; Complete source code: ...
Hello, I have a MMORPG emulator, this means it will be handling packets quite a bit. Currently, I am using pointers for this, as I think when used correctly, they can speed up my server, however I've got two friends, one is telling me to use pointers, he thinks I can use them without running into trouble, my other friends says I should n...
I first process a matrix in cublas, I have already sent it to device and I want to process some column vector of the matrix, still use cublas function. I first try using pointer arithmetic operation to offset the device pointer from host, but it seems doesn't work. Is there any way I can process vector in matrix without copying it back t...
I understand that in order to return a string from a function I have to return a pointer. What I don't understand is why a char array is treated somewhat different from, say, integer, and gets destroyed when you exit the function. That's probably because I come from a high-level languages world, but this seems to be equally valid to me: ...
I intend to store strings into an array of pointers to strings and then display them as follows : char *directions[3]; for(i=0;i<3;i++) scanf("%s",directions[i]); for(i=0;i<3;i++) printf("%s",directions[i]); but when i run this code ,it gives me segmetation fault ,could someone please correct me? ...
What am I doing wrong here ? /* * Consider the following pseudo code ! */ typedef struct foobar { unsigned char id, count; struct foobar *child; } foobar; foobar root = (foobar *) malloc( sizeof(struct foobar) ); root->child = (foobar *) malloc( sizeof(struct foobar) ); root->count++; root->child[0].id = 1; root->count++; r...
Hello, gcc 4.4.3 c89 I have the following source file. However, I get a stack dump on the following line: printf("dest: %d [ %s ]\n", i, dest[i]); The reason is that if fails to break from the for loop. I have tried different conditions in the for loop to try and break before printing. i != NULL i != '\0' i != 0 However, all of...
My main() crashes below when add(4) is called. As I understand int* add, it should return a pointer to integer. Then, I should be able in main to say: int * a = add(3); to return a pointer to int. Please explain what I'm doing wrong. #include <cstdlib> #include <iostream> using namespace std; int* add (int a) { int * c, d; ...
How do I pass the m matrix to foo()? if I am not allowed to change the code or the prototype of foo()? void foo(float **pm) { int i,j; for (i = 0; i < 4; i++) for (j = 0; j < 4; j++) printf("%f\n", pm[i][j]); } int main () { float m[4][4]; int i,j; for (i = 0; i < 4; i++) for (j = 0; j ...
hi, Just getting into C++. I'm getting constantly thrown off track when I see the symbol for multiply (*) being used to denote the dereferencing of a variable for example: unsigned char * pixels = vidgrabber.getPixels(); Does this throw other people off? What's the tip for getting my head around this? Thank you. p.s. I have an...
As background, I gave an answer to this post a little while ago: http://stackoverflow.com/questions/3473438/c-return-array-in-a-function/3473448#3473448 And it unintentionally kicked off a really long comment chain about pointers vs. arrays in C++ because I tried to oversimplify and I made the statement "arrays are pointers". Though m...
Which is the better convention of declaring pointers in C++? MyClass* ptr (or) MyClass *ptr I find the first one meaningful, because i feel like declaring MyClass pointer rather than a MyClass and specifying a type modifier. But i see a lot of books recommending the later convention. Can you give the rational behind the convention...
I have code that interacts with a gridview, and the code is exactly the same for multiple gridviews. So can I do something like this: Dim gridViewPointer As GridView If (gridViewNumber = 1) Then gridViewPointer = GridView1 ElseIf (gridViewNumber = 8) Then gridViewPointer = GridView8 ... ...