GeeksforGeeks » C/C++ Programming Questions
A C malloc() and free() question
(4 posts)-
void f(int y) { struct s *ptr; ptr = malloc (sizeof (struct)+99*sizeof(int)); } struct s { int i; float p; };when free (ptr) is executed, then what will happen?
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The argument to malloc is size_t type. The expression "sizeof (struct)+99*sizeof(int)" returns a constant of size_t type. What ever may be the constant malloc allocates that much size, and free can freeup same when called.
melloc return void*, hence can be easily assigned to ptr (structure pointer). It is up to the programming to face the consequences if used without proper memory allocation.
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I think the question is what happens when you free a ptr outside the function.
Here ptr is local to function f() , so when you come out of that function ptr is dead, so you cant use or free that ptr.
Pls correct me if I'm wrong. -
It is what we call as memory leak. If we come out of function, the scope of ptr will be over. There will be no question of freeing ptr. I guess the question is on incorrect allocation of space and accessing it by structure 's' pointer.
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