How do I use the SIGALRM correctly?

Question

I'm made this code, and I have to use the alarm signal (SIGALRM) to make the program print the message “I am alive.” every 3 seconds.

But it doesn't work, it sends the message "I'm Alive" only when I press CTR-C, I'm guessing I didn't put the SIGALRM function in the right place, can you help me?

#include <stdlib.h>
#include <signal.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>

unsigned Count = 0; //Counts the number of times it receives the signal SIGINT.
void mypause(int sign); //prototype of the function my pause.

void mypause(int sign) {
  signal(SIGALRM, mypause); //Set alarm clock for 3 seconds.
  alarm(3);
  printf("I'm Alive");
  signal(SIGINT, mypause);
  switch (sign) {
  case SIGINT:
    printf("\nPressed CTR-C\n");
    printf("I'm running, waiting for a sign\n");
    Count++;
    break;
  case SIGQUIT:
    printf("\nPressed CTR-\\n");
    printf("You pressed CTR-C %d times", Conta);
    exit(0); //Exit program.
    break;
  }
}

int main() {
  signal(SIGALRM, mypause);
  signal(SIGINT, mypause);
  signal(SIGQUIT, mypause);
  printf("\nI'm running waiting for a signal\n");
  while (1) {}
  return (0);
}

Answer 1

Maybe add alarm(3) in your main() ?