Which of the following experts can see where the problem is?

Which of the following experts can see what the problem is-General Linux technology-Linux programming and kernel information? The following is a detailed description. # Include "apue. h"

Static void sig_quit (int );

Int main ()
{
Sigset_t newmask, oldmask, pendmask;

If (signal (SIGQUIT, sig_quit) = SIG_ERR)
Err_sys ("can't catch SIGQUIT ");

Sigemptyset (& newmask );
Sigaddset (& newmask, SIGQUIT-1 );

If (sigprocmask (SIG_BLOCK, & newmask, & oldmask) <0)
Err_sys ("SIG_BLOCK error ");

Sleep (5 );

If (sigpending (& pendmask) <0)
Err_sys ("sigpending error ");
If (sigismember (& pendmask, SIGQUIT-1) <0)
Printf ("\ nSIGQUIT pending \ n ");

If (sigprocmask (SIG_SETMASK, & oldmask, NULL) <0)
Err_sys ("SIG_SETMASK error ");
Printf ("SIGQUIT unblocked \ n ");

Sleep (5 );
Exit (0 );
}

Static void sig_quit (int signo)
{
Printf ("caught SIGQUIT \ n ");
If (signal (SIGQUIT, SIG_DFL) = SIG_ERR)
Err_sys ("can't reset SIGQUIT ");
}
Press ctrl + \ to output the result:
SIGQUIT pending
Catch SIGQUIT
SIGQUIT unblocked
However, my running result does not output SIGQUIT pending, that is
Catch SIGQUIT
SIGQUIT unblocked
Why?