Can you access other program's memory using program compiled with mingw?

Question

I wrote this very simple program on Windows 8.1 and compiled it using gcc from Mingw. I ran it with "test.exe > t.txt" and "test.exe > t1.txt" and the outputs were different (even though it uses virtual addresses). It ran for a while and then it crashed. I decided to test this because I'm reading a book on operating systems.

Is it reading other programs' memory? Wasn't that not supposed to happen? I'm probably misunderstanding something...

#include <stdio.h>

int main(int argc, char *argv[]){
    int r = 0;
    int p[4] = {1,5,4,3};

    for(r=0; p[r]!=1111111111111111; r++){
        p[2] = p[r];
        printf("%d\n", p[2]);
    }

    return 0;
}

Thank you.

Answer 1

SadSeven, I assume you are reading past the end of the array on purpose. What you are seeing is not other programs memory, it's uninitialized memory inside of your programs memory.

Every program runs inside it's own virtual memory space, the os's virtual memory manager takes care of this. You can't access another programs memory from your program (unless you are both using shared memory, but you have to do that on purpose)