6.c

// PRODUCER-CONSUMER PROBLEM USING SEMAPHORES
#include <stdio.h>
#include <stdlib.h>
int mutex = 1, full = 0, empty = 3, x = 0;
int signal(int s)
{
    return (++s);
}
int wait(int s)
{
    return (--s);
}
void producer()
{
    empty = wait(empty);
    mutex = wait(mutex);
    x++;
    printf("\nProducer Produces the item %d ", x);
    mutex = signal(mutex);
    full = signal(full);
}
void consumer()
{
    full = wait(full);
    mutex = wait(mutex);
    printf("\nConsumer Consumes the item %d ", x);
    x--;
    mutex = signal(mutex);
    empty = signal(empty);
}
void main()
{
    int n;
    while (1)
    { 
        printf("\n1.PRODUCER\n2.CONSUMER\n3.EXIT\n");
        printf("\nENTER YOUR CHOICE\n");
        scanf("%d", &n);
        switch (n)
        {
            case 1:
                if ((mutex == 1) && (empty != 0))
                    producer();
                else
                    printf("\nBUFFER IS FULL\n"); 
                break;
            case 2:
                if ((mutex == 1) && (full != 0)) 
                    consumer();
                else
                    printf("\nBUFFER IS EMPTY\n"); 
                break;
            case 3:
                exit(0);
            break;
        }
    }
}