Syntax:

    #include <csignal>
    void ( *signal( int signal, void (* func) (int)) ) (int);

The signal() function sets func to be called when signal is recieved by your program. func can be a custom signal handler, or one of these macros (defined in the csignal header file):

Macro Explanation SIG_DFL default signal handling SIG_IGN ignore the signal

Some basic signals that you can attach a signal handler to are:

Signal Description SIGTERM Generic stop signal that can be caught. SIGINT Interrupt program, normally ctrl-c. SIGQUIT Interrupt program, similar to SIGINT. SIGKILL Stops the program. Cannot be caught. SIGHUP Reports a disconnected terminal.

The return value of signal() is the address of the previously defined function for this signal, or SIG_ERR is there is an error. Example code: The following example uses the signal() function to call an arbitrary number of functions when the user aborts the program. The functions are stored in a vector, and a single “clean-up” function calls each function in that vector of functions when the program is aborted:

  void f1() {
    cout << "calling f1()..." << endl;
  }

  void f2() {
    cout << "calling f2()..." << endl;
  }

  typedef void(*endFunc)(void);
  vector<endFunc> endFuncs;

  void cleanUp( int dummy ) {
    for( unsigned int i = 0; i < endFuncs.size(); i++ ) {
      endFunc f = endFuncs.at(i);
      (*f)();
    }
    exit(-1);
  }

  int main() {

    // connect various signals to our clean-up function
    signal( SIGTERM, cleanUp );
    signal( SIGINT, cleanUp );
    signal( SIGQUIT, cleanUp );
    signal( SIGHUP, cleanUp );

    // add two specific clean-up functions to a list of functions
    endFuncs.push_back( f1 );
    endFuncs.push_back( f2 );

    // loop until the user breaks
    while( 1 );

    return 0;
  }

Related Topics: raise