#include <stdio.h>

int * add(int x, int y) {
    int z = x + y;
    int *ans_ptr = &z;
    return ans_ptr;
}

int main() {
    int ans = *(add(1, 2));
    int *ans_ptr = add(1, 2);

    printf("%dn", *ans_ptr);
    printf("%dn", ans);

    return 0;
}

int * add(int x, int y) {
    int z = x + y; //z is a local variable in this stack frame
    int *ans_ptr = &z; // ans_ptr points to z
    return ans_ptr;
}


// at return of function, z is destroyed, so what does ans_ptr point to? No one knows.  UB results

ccc-analyzer -c foo.c
...
ANALYZE: foo.c add
foo.c:6:5: warning: Address of stack memory associated with local
                    variable 'z' returned to caller
    return ans_ptr;
    ^      ~~~~~~~