Hello, I wrote a C program in Linux that mallocs memory, ran it in a loop, and TOP didn't show any memory consumption. then I've done something with that memory, and TOP did show memory consumption. When I malloc, do I really "get memory", or is there a "lazy" memory management, that only gives me the memory if/when I use it? (There...
Hey everyone, I am getting a heap corruption error I cannot figure out. char * c = (char *) malloc(1); // main loop _gcvt_s(c, 100, ball->get_X_Direction(), 10); if(pushFont(c, (SCREEN_WIDTH - 30), (SCREEN_HEIGHT - 40), message, screen, font, textColor) == false) { //return 1; // error rendering text. } // end main loop f...
On Linux if I were to malloc(1024 * 1024 * 1024), what does malloc actually do? I'm sure it assigns a virtual address to the allocation (by walking the free list and creating a new mapping if necessary), but does it actually create 1 GiB worth of swap pages? Or does it mprotect the address range and create the pages when you actually to...
Assuming the latest XCode and GCC, what is the proper way to override the memory allocation functions (I guess operator new/delete as well). The debugging memory allocators are too slow for a game, I just need some basic stats I can do myself with minimal impact. I know its easy in Linux due to the hooks, and this was trivial under code...
I have a struct that only contains pointers to memory that I've allocated. Is there a way to recursively free each element that is a pointer rather than calling free on each one? For example, let's say I have this layout: typedef struct { ... } vertex; typedef struct { ... } normal; typedef struct { ... } texture_coord; typedef struct...
Hello guys, I have this code snippet below and it crashes during the assignment in 'str', a dynamic allocation. char *str; int file_size; FILE *fptr; if (!(fptr = fopen(filename, "r"))) goto error1; if ((fseek(fptr, 0L, SEEK_END) != 0)) goto error2; if (!(file_size=ftell(fptr))) goto error2; if ((fseek(fptr, 0L, SEEK_SET)...
Hello I'm programming an application in Objective-C and I'm getting this error: MyApp(2121,0xb0185000) malloc: *** error for object 0x1068310: double free *** set a breakpoint in malloc_error_break to debug It is happening when I release an NSAutoreleasePool and I can't figure out what object I'm releasing twice. How do I set his br...
Possible Duplicate: Malloc thread-safe? I heard that glibc malloc() was not thread safe, since several threads of a process calling malloc() simultaneously will lead to undefined behaviour. And my question is if a thread calls free() will another thread is calling malloc(), will this lead to undefined behaviour as well? ...
As I loop through lines in file A, I am parsing the line and putting each string (char*) into a char**. At the end of a line, I then run a procedure that consists of opening file B, using fgets, fseek and fgetc to grab characters from that file. I then close file B. I repeat reopening and reclosing file B for each line. What I would ...
Hi all, I d love to know how I can allocate data through a function, and after the function is returned the data is still allocated. This is both for basic types (int, char**) and user defined types. Below are two snipsets of code. Both have the allocation within the function though after the return the allocation goes. int* nCheck = N...
When using malloc and doing similar memory manipulation can I rely on sizeof( char ) being always 1? For example I need to allocate memory for N elements of type char. Is multiplying by sizeof( char ) necessary: char* buffer = malloc( N * sizeof( char ) ); or can I rely on sizeof( char ) always being 1 and just skip the multiplicatio...
Alloca allocates memory from Stack rather then heap which is case in malloc. So, when I return from the routine the memory is freed. So, actually this solves my problem of freeing up of dynamically allocated memory . Freeing of memory allocated through malloc is a major headache and if somehow missed leads to all sorts memory problems. ...
How do I allocate memory for a char variable (not a char pointer) inside a struct? (Variable names are in portuguese, sorry if it's kinda confusing) I have this struct: typedef struct node{ char rotulo[10], instrucao[1][2][10], flag; int simplificado; struct node *referencias[2]; struct node **antecessores; int n...
In my company there is a coding rule that says, after freeing any memory, reset the variable to NULL. For example ... void some_func () { int *nPtr; nPtr = malloc (100); free (nPtr); nPtr = NULL; return; } I feel that, in cases like the code shown above, setting to NULL does not have any meaning. Or am I missin...
A friend of mine was asked, during a job interview, to write a program that measures the amount of available RAM. The expected answer was using malloc() in a binary-search manner: allocating larger and larger portions of memory until getting a failure message, reducing the portion size, and summing the amount of allocated memory. I beli...
Hi there, I have a program that basically looks like: typedef struct cpl_def { int A; int B; int OK; struct cpls *link; }cpls; int main(void) { int n1, n2; int num = 300; /* say */ int *a; ...
Hello. I made a small function to catenate strings and return the combined string. However since I assign memory to a third variable in the function, will the memory be freed when the function finishes or will it stay there, requiring me to free it later? and if I need to free it, what's the most stylish solution to do it? Here's the te...
Hi all, I am facing a problem on malloc for allocating memory: ByteArr = (BYTE *)malloc(sizeof(SHORT) * 20); I m getting error like "CXX0030: Error: expression cannot be evaluated" But if i am taking 428 or 1024 instead of 20 than its allocating the memory.Can you please tell me where is the problem ...thanks. ...
Very simple question, I made the following program : #include <stdlib.h> int main(int argc, char ** argv) { void * ptr; ptr = malloc(0); free(ptr); } And it does not segfault on my machine. Is it a portable behaviour of stdlib malloc and free, or am I looking for trouble ? Edit : What seems non portable is the value retur...
I've a question about the memory management in C (and GCC 4.3.3 under Debian GNU/Linux). According to the C Programming Language Book by K&R, (chap. 7.8.5), when I free a pointer and then dereference it, is an error. But I've some doubts since I've noted that sometimes, as in the source I've pasted below, the compiler (?) seems to work...