Thread: freeing allocated memory

Can I free something if it was declared like that: char str[100] ?


Thanks.

The heap and stack have always interested me, where can I read more on the subject?


Thanks.

The heap is a block of storage that a program can allocate and deallocate when needed.

The system stack is a storage location for variables and function calls. Information is pushed on the stack when, for example, a function is called or variables are declared, and popped from the stack when the function exits.

Lets say char str[100] is declared in a function so it has automatic storage duration:

void funcExample(void)
{
int x;

char str[100];

....(other things)

return;
}

Each time funcExample is called, an "activation record" is created.
An activation record is a data structure on the "stack" that holds the variables for an invocation of a function. The activation record holds a set of the variables of funcExample (x, and str);

Storage is allocated for that str. On return from funcExample, the storage is deallocated.

On the other hand, if char str[100] is declared outside of any function, str has static duration and external linkage. The array is allocated on the heap, but free cannot be used on it. It stays there until the program ends.

Hope that helps.

Thanks alot guys