Why system doesn't return main's value?

[root@ test]$ cat return1开发者_如何转开发0.c
#include <stdio.h>
int main(int argc, char *argv[]){
    return 10;
}
[root@ test]$ perl -e 'print system("/path_to_return10")'
2560

I was expecting 10 but got 2560,why?

See $? in perldoc perlvar.

You got 10 * 256 (return value = 10) + 0 * 128 (there was no core dump) + 0 (process wasn't killed by signal).

as specified in the documentation for the system call in perl (http://perldoc.perl.org/functions/system.html):

The return value is the exit status of the program as returned by the wait call. To get the actual exit value, shift right by eight (see below).

indeed: 2560 >> 8 = 10