ex2 w5 3

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

#define MAX_MESSAGE_LENGTH 256

// Define the struct Thread
struct Thread {
    pthread_t id;
    int i;
    char message[MAX_MESSAGE_LENGTH];
};

// Mutex for synchronization
pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
int current_thread_index = 0; // Index of the thread that should execute next

// Function to be executed by each thread
void* thread_function(void* arg) {
    struct Thread* thread_data = (struct Thread*)arg;

    // Create the message
    snprintf(thread_data->message, MAX_MESSAGE_LENGTH, "Hello from thread %d", thread_data->i);

    // Synchronize thread execution
    pthread_mutex_lock(&mutex);

    // Ensure that the current thread is the one that should execute next
    while (thread_data->i != current_thread_index) {
        pthread_mutex_unlock(&mutex);
        pthread_mutex_lock(&mutex);
    }

    // Output the ID and message
    printf("Thread %d: %s\n", thread_data->i, thread_data->message);

    // Update the current_thread_index
    current_thread_index++;

    pthread_mutex_unlock(&mutex);

    return NULL;
}

int main(int argc, char* argv[]) {
    if (argc != 2) {
        printf("Usage: %s <number_of_threads>\n", argv[0]);
        return 1;
    }

    int n = atoi(argv[1]);

    if (n <= 0) {
        printf("Please provide a positive number of threads.\n");
        return 1;
    }

    struct Thread threads[n];

    for (int i = 0; i < n; i++) {
        threads[i].i = i;
        printf("Thread %d is created\n", i);

        if (pthread_create(&threads[i].id, NULL, thread_function, &threads[i]) != 0) {
            perror("pthread_create");
            return 1;
        }
    }

    // Wait for all threads to finish
    for (int i = 0; i < n; i++) {
        pthread_join(threads[i].id, NULL);
    }

    return 0;
}