What are event flags in C and can you provide examples?

What are event flags in C and can you provide examples?

Event flags in C are used for synchronization between tasks, especially in real-time operating systems. They allow tasks to signal each other about events.

Can you give me a code example of how to use event flags?

Sure! Here's a simple example:

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <semaphore.h>

sem_t event_flag;

void* task1(void* arg) {
    printf("Task 1 is running...\n");
    sleep(1);
    sem_post(&event_flag); // Signal that Task 1 is done
    return NULL;
}

void* task2(void* arg) {
    sem_wait(&event_flag); // Wait for Task 1 to finish
    printf("Task 2 is running after Task 1...\n");
    return NULL;
}

int main() {
    pthread_t t1, t2;
    sem_init(&event_flag, 0, 0);
    pthread_create(&t1, NULL, task1, NULL);
    pthread_create(&t2, NULL, task2, NULL);
    pthread_join(t1, NULL);
    pthread_join(t2, NULL);
    sem_destroy(&event_flag);
    return 0;
}

What happens if I don't use event flags?

Without event flags, tasks may run into race conditions or execute out of order, leading to unpredictable behavior in your program.