Function returns the malloc'ed value.?

[Jack S]

Hello!

My function e.g. foo returns the malloc'ed value (pointer).

int *foo(int size){
int *tmp;
tmp=malloc(sizeof(int)*size);
if(tmp != NULL) {
tmp[2]=5;
}
return tmp;
}


Where should the allocated memory be freed? In the function, where I'm calling it?

main(){
int *ar1, size=10;
ar1 = foo(size);
if(ar1 != NULL) {
ar1[1]=6;
}
free (ar1);
}

Is that OK? My doubts are: I actually didn't allocate ar1. And according to my C/C++ Reference Guide "You can only free () a pointer, which is allocated by malloc/calloc etc."

Could someone explain to me how does it work?

And the second question:

Could I somehow prove whether the memory has been freed?
Is there any function in C for this?

Thank you very much.