C++ Signal Handling

In C++ Signals are software interrupts delivered to a process by the operating system.

To pressing Ctrl+C helps to generate interrupts on Unix, Linux, and windows system.

The following list of signals which you can catch in your program.

The signal() Function

The signal() function provides a function signal to trap unexpected events through the signal-handling library.

Syntax:

void (*signal (int sig, void (*func)(int)))(int);

The signal() function had two arguments:

• An integer which represents the signal number.
• A pointer to the signal-handling function.

The raise() Function

The raise() function helps to send the signal which takes an integer signal number.

Syntax:

int raise (signal sig);

sig is the signal number to send following one of the signals:

SIGINT, SIGABRT, SIGFPE, SIGILL, SIGSEGV, SIGTERM, SIGHUP.

Example:

#include <iostream>
#include <csignal>
using namespace std;

sig_atomic_t signalled = 0; 
void handler( int signalnumber ) 
{
    cout << "Interrupt signal (" << signalnumber << ") received.\n";
    signalled=1;     
}
int main () {
    // register signal SIGINT and signal handler  
    signal(SIGINT, handler);  
    raise(SIGINT); 
    if (signalled)  
        cout << "Signal is handled";  
    else  
        cout << "Signal is not handled";  
    return 0;
}