C library functions -sigemptyset()

C Standard Library - <signal.h>

sigpendingThe function is a function in the C standard library, used to obtain the pending signal set of the current process. Pending signals are signals that have been blocked but not yet processed. This function is defined in<signal.h>In the header file.

Syntax

<code>int sigemptyset(sigset_t *set);</code>

Parameter

  • sigset_t *set: points to asigset_ta variable of type, which will be initialized to an empty signal set.

Return Value

  • Returns 0 on success.
  • On failure, returns -1 and setserrnoto indicate the type of error.

Example

The following is an example usingsigemptysetAn example program for the function to initialize a signal set. The program initializes a signal set and checks whether it contains a specific signal.

Example

#include <stdio.h>
#include <signal.h>

int main() {
    sigset_t set;

    // Initialize the signal set to empty
    if (sigemptyset(&set) == -1) {
        perror("sigemptyset");
        return 1;
    }

    // Check whether the signal set contains SIGINT
    if (sigismember(&set, SIGINT)) {
        printf("SIGINT is in the set\n");
    } else {
        printf("SIGINT is not in the set\n");
    }

    return 0;
}

After compiling and running the program, the output will be:

SIGINT is not in the set

The program first blocksSIGINTsignal, then sends that signal, and usessigpendingChecksSIGINTwhether it is in the pending signal set. Finally, the program restores the original signal mask and catchesSIGINTsignal, executes the signal handler.

Parsing

  • sigset_t set;: defines a signal set variable.
  • UsagesigemptysetThe function initializes the signal set to empty.
  • UsagesigismemberThe function checks whether the signal set containsSIGINTsignal.
  • The output showsSIGINTThe signal is not in the initialized empty signal set.

Notes

  • sigemptysetThe function is used to initialize a signal set so that it does not contain any signals.
  • The initialized signal set can be used for subsequent signal operations, such as adding or removing signals.

C Standard Library - <signal.h>

other extensions