SO P&T - 4

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

char ch = 'a';
pthread_mutex_t mtx = PTHREAD_MUTEX_INITIALIZER;


void* print_ch(void*value){
    pthread_mutex_lock(&mtx);
    printf("%c", ch);
    ch++;
    pthread_mutex_unlock(&mtx);
    return NULL;
}

int main(){
    pthread_t arr[3];

    int i;
    for(i = 0; i < 3; i++){
        pthread_create(&arr[i], NULL, &print_ch, NULL);
    }

    for(i = 0; i < 3; i++){
        pthread_join(arr[i], NULL);
    }

    putchar('\n');
}