c - Why is waitpid not waiting for a process to quit? -

i have simple code written in c , os osx:

int main() {     pid_t pid = 1244;     int pid_status;     waitpid(pid, &pid_status, 0);     printf("%i\n",pid_status); } 

1244 process id opera browser running right now:

korays-macbook-pro:helloworld koraytugay$ ps -p 1244   pid tty           time cmd  1244 ??         0:09.19 /applications/opera.app/contents/macos/opera 

what expect happen when run program, should wait until close opera, is:

korays-macbook-pro:helloworld koraytugay$ ./koko 1798668342 korays-macbook-pro:helloworld koraytugay$ ./koko 1637806134 korays-macbook-pro:helloworld koraytugay$ ./koko 1707163702 

why program directly quitting , these different numbers?

waitpid effective child processes. see manual page http://man7.org/linux/man-pages/man2/wait.2.html.

you find waitpid returning -1. please check errno