C program that prints 2+2=5. http://codegolf.stackexchange.com/questions/28786/write-a-program-that-makes-2-2-5

225.c

#include <stdio.h>

void hack() {
    int start = 0;
    int *p=&start;

    /* start moving up the stack until we find the marker. */
    while (*p != 0x12345678)
        p++;

    /* set x to 3 */
    p[-1] = 3;
}

int main() {
    int marker = 0x12345678;
    int x = 2;
    int y = 2;
    hack();
    printf("%d\n", x+y);
    return 0;
}