how can I execute c program under another one

How can I execute a c program under another one. Assume you have one c code (program), and you want to call another one. Because you want to send input to it then score its return data with comparing another expected return data.

try.c

int main(void) {
    for (i = 0; i < MA开发者_StackOverflowX; ++i) {
        /* call another program ( namely, try2.c ) to give it a single input,
        then measure its returning data /*
    }
    return 0;
}

try2.c reside in another FILE.

Compiler is gcc, and under system linux

system, popen or platform depended features like fork and exec