/*

Run at CSE like this

$ clang -Wno-everything  invalid2.c -o invalid2
$ ./invalid2
answer=42

*/

#include <stdio.h>

void f(int x);

int main(void) {
    int answer = 36;
    printf("answer is stored at address %p\n", &answer);

    f(5);
    printf("answer=%d\n", answer); // prints 42 not 36

    return 0;
}

void f(int x) {
    int a[10];

    // a[18] doesn't exist
    // on CSE servers  (clang 7.0 x86_64/Linux)
    // variable answer in main happens to be where a[19] would be

    printf("a[18] would be stored at address %p\n", &a[18]);

    a[18] = 42;
}