sigprocmask() question!

#include <sys/types.h>
#include <signal.h>
#include <stdlib.h>
#include <stdio.h>

int main(void)
{
sigset_t sigSet, sigOutSet;

sigemptyset(&sigSet);

sigaddset(&sigSet, SIGUSR1);

sigprocmask(SIG_SETMASK, &sigSet, &sigOutSet);

printf("sigSet = %d\n", sigSet);
printf("sigOutSet = %d\n", sigOutSet);

exit(0);
}

why is not equal. I think sigSet equal sigOutSet. why???

----------------解决方案--------------------------------------------------------
?啥意思啊 sigSet sigOutSet都是sigset_t类型啊 什么叫相等
----------------解决方案--------------------------------------------------------