< c‎ | program
Defined in header <signal.h>
typedef /* unspecified */ sig_atomic_t;

An integer type which can be accessed as an atomic entity even in the presence of asynchronous interrupts made by signals.

[edit] Example

#include <signal.h>
#include <stdio.h>
volatile sig_atomic_t gSignalStatus = 0;
void signal_handler(int signal)
    gSignalStatus = signal;
int main(void)
    /* Install a signal handler. */
    signal(SIGINT, signal_handler);
    printf("SignalValue:   %d\n", gSignalStatus);
    printf("Sending signal %d\n", SIGINT);
    printf("SignalValue:   %d\n", gSignalStatus);

Possible output:

SignalValue:   0
Sending signal 2
SignalValue:   2

[edit] See also

sets a signal handler for particular signal
C++ documentation for sig_atomic_t