c - change a pointer of address of another application -

i need edit title, can't find better title.

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assume have simple program called source.exe:

#include <stdio.h>  int main() {    int = 5;    printf("%p", &a);    return 0; } 

i want write application, change.exe, changes a in above.

i tried this:

int main() {    int * p = (int*) xxx; // xxx have printed above    *p = 1;    printf("%d", *p);    return 0; } 

it doesn't work. assuming have administrator rights, there way i've tried above? thanks.

in first place, when run second program, a in first long gone (or loaded in different position). in second place, many os's protect programs loading them in separate spaces.

what seem looking inter-process communication (ipc) mechanisms, shared memory or memory-mapped files.