If I have the next function
Stack *construct_stack(void) {
Stack *instance = (Stack *) malloc(sizeof(Stack));
// Stuff...
return instance;
}
It's sort of "constructor". But I'v been having problems with the "destructor".
If I do this I get an error.
void destruct_stack(Stack **st) {
// Stuff...
free(st);
}
Some idea?
void destruct_stack(Stack **st) {
// Stuff...
free(*st);//free the pointer which st points to
*st = NULL;//set it to null
}
And You don't need to cast the result of malloc: Do I cast the result of malloc?
void destruct_stack(Stack **st)
Here st is pointer to pointer(i.e instance) to which you allocate memory (st holds address of pointer instance).
free(st); // you didn't allocate memory to st therefore gives error
So you should free *st like this
free(*st);
*st=NULL; // just a good practice
Or another way instead of address of the pointer(i.e &instance) you can pass the pointer instance itself and then free it but you will need to change the type of parameter which is passed to function.
free(*st);*st=NULL;Stack *s = construct_stack(); // Stuff... destruct_stack(&s);