sp-lab/3.c

#include<stdio.h>
#include<semaphore.h>
#include<fcntl.h>

int main(){
    int read_count = 0;
    int data= 0;

    sem_unlink("/mutex"); sem_unlink("/wrt");
    sem_t *mutex = sem_open("/mutex", O_CREAT, 0644, 1);
    sem_t *wrt = sem_open("/wrt", O_CREAT, 0644, 1);

    int choice;
    while(1){
    printf("\n1.Read");
    printf("\n2.Write");
    printf("\n3.exit");
    printf("\nEnter the choice: ");
    scanf("%d", &choice);

    if(choice ==1){
        sem_wait(mutex);
        read_count++;
        if(read_count==1)
            sem_wait(wrt);
        sem_post(mutex);

        printf("read data: %d | Active readers: %d", data, read_count);

        sem_wait(mutex);
        read_count--;
        if(read_count==0)
            sem_post(wrt);
        sem_post(mutex);
    }
    else if(choice ==2){
        sem_wait(wrt);
        data+=10;
        printf("wrote data: %d", data);
        sem_post(wrt);
    }else{
        break;
    }

    }
        sem_close(mutex);
    sem_close(wrt);
    sem_unlink("/mutex");
    sem_unlink("/wrt");



    return 0;
}