alarm() Function 🎯Welcome to our comprehensive guide on the alarm() function in C programming! This tutorial is designed to help you understand the concept from scratch and by the end, you'll be able to use it confidently in your own projects.
alarm() Function? 📝The alarm() function is a part of the POSIX standard library and is used to set an alarm that generates a signal after a specified time. In C programming, it's particularly useful for scheduling tasks and managing time-sensitive operations.
alarm() Function? 💡alarm() to schedule periodic tasks that need to run after specific intervals.alarm() can help manage the execution time of your programs by setting time limits.The alarm() function has one argument - the number of seconds for which the alarm should be set. Here's the syntax:
#include <unistd.h>
int alarm(unsigned int seconds);The function returns the previous alarm value if successful, or -1 if an error occurs.
Let's create a simple example where we set an alarm for 10 seconds and print a message when the alarm goes off.
#include <stdio.h>
#include <unistd.h>
#include <signal.h>
void alarm_handler(int signum) {
printf("Alarm went off!\n");
}
int main() {
signal(SIGALRM, alarm_handler);
alarm(10);
printf("Setting the alarm for 10 seconds...\n");
pause(); // pause execution until a signal is received
printf("Alarm program ended.\n");
return 0;
}In this example, we first define an alarm_handler function that will be called when the alarm signal (SIGALRM) is received. Next, we set the alarm for 10 seconds and create a pause() to wait for the alarm.
In this example, we'll create a program that prints the current time every 5 seconds.
#include <stdio.h>
#include <unistd.h>
#include <sys/time.h>
#include <signal.h>
void alarm_handler(int signum) {
struct timeval tv;
gettimeofday(&tv, NULL);
printf("Current time: %d:%02d:%02d\n", tv.tv_sec, tv.tv_usec / 100000, tv.tv_usec % 100000);
}
int main() {
signal(SIGALRM, alarm_handler);
while (1) {
alarm(5);
pause();
}
return 0;
}In this example, we've created an infinite loop where the alarm is set every 5 seconds, and the program pauses until the alarm goes off. Inside the alarm_handler, we get the current time and print it.
Which header file do you need to include to use the `alarm()` function?