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

volatile unsigned int alarmTrig;

static void alrmHandler(int x)  //indicates alarm triggered and resets same
{
        alarmTrig = 1;
        alarm(1);
        return;
}

int main(int argc, char *argv[])
{
        struct sigaction theHandler;    //sigaction struct
        char inpChar;
        int i, bytesRead = 0;
        sigset_t emptyMask;

        sigemptyset(&emptyMask);
        theHandler.sa_handler = alrmHandler;
        theHandler.sa_mask = emptyMask; //nothing special
        theHandler.sa_flags = 0;        //nothing special here
        theHandler.sa_restorer = NULL;  //option obsolete

        sigaction(SIGALRM, &theHandler, NULL);
        alarmTrig=0;

        alarm(1);
        for(i=0; i<20; i++)
        {
                while(alarmTrig == 0)
                {
                        bytesRead = fread(&inpChar, 1, 1, stdin);
                        if(bytesRead == 1)
                        {
                                printf("You entered %c.\n",inpChar);
                        }
                }
                if (alarmTrig == 1)
                {
                        alarmTrig=0;
                        printf("%d seconds have gone by.\n",i);
                        alarm(1);
                }
        }

        return 0;
}

__BEGIN_NAMESPACE_STD

and 

__END_NAMESPACE_STD