i'm just lost.. in memory allocation

[pan nudus]

hi all gurus, well.. i'm lost. i'm sure anyone of you can pick me up, because this seems to be really basic knowledge i'm missing here.

struct ListElement
{
	struct ListElement *next;
	char* URL;
};

//////////////

char *data = "blaaaaaaaalb\0";

ListElement *listptr = (struct ListElement*)malloc(sizeof(ListElement));
listptr->next = NULL;
listptr->URL = (char*)malloc(strlen(data)+1);
listptr->URL = data;

listptr->URL = (char*)realloc(listptr->URL, strlen(data)+1);

at the line with realloc() it gives me a "user breakpoint called from code .." both in debug and release mode. what am i doing wrong here? i just want to assign a different string to URL and therefore need to reallocate. i also tried with free()'ing listptr->URL followed by a malloc(), but the same happens at free(listptr->URL).

thanks for ur time.

[Richie T]

eh wrong forum there, someone move this to C where it
belongs!!?

[Tonto]

No that's kinda C++. He doesn't typedef the struct the whole time, malloc/realloc is legal and he casts it. Problem:

listptr->URL = (char*)malloc(strlen(data)+1);
listptr->URL = data;

listptr->URL = (char*)realloc(listptr->URL, strlen(data)+1);

You allocate memory, then reassign the pointer (memory leak), and then try to realloc something that wasn't originally allocated with realloc/malloc/calloc or is NULL, so it prolly crashes.

listptr->URL = (char*) malloc(strlen(data)+1);
strcpy(listptr->URL, data);

listptr->URL = (char*)realloc(listptr->URL, strlen(data)+1); // Block is the same size still...

[pan nudus]

cheers! i love C

i don't need the realloc() then too (for assigning other data possibly longer), i can just make a _strdup(new_data_that_might_be_longer) and thats it.

thanks for the quick help.