IPC SystemV Semaphores

#include <stdio.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <stdlib.h>
#include <sys/sem.h>
#include <time.h>
#define SHMSIZE 1

union semun
{
    int val;
    struct semid_ds *buf;
    unsigned short *array;
};

int main()
{
    pid_t pid;
    key_t key;
    char *buff;
    int shmid;
    char symbol;
    int semid;
    key = ftok(".", 1);
    semid = semget(key, 2, IPC_CREAT | 0755);
    union semun un;
    unsigned short arr[2] = { 1, 0 };
    un.array = arr;
    semctl(semid, 0, SETALL, un);

    struct sembuf popProduce;
    popProduce.sem_num = 0;
    popProduce.sem_op = -1;
    popProduce.sem_flg = 0;

    struct sembuf vopProduce;
    vopProduce.sem_num = 0;
    vopProduce.sem_op = 1;
    vopProduce.sem_flg = 0;

    struct sembuf popConsume;
    popConsume.sem_num = 1;
    popConsume.sem_op = -1;
    popConsume.sem_flg = 0;

    struct sembuf vopConsume;
    vopConsume.sem_num = 1;
    vopConsume.sem_op = 1;
    vopConsume.sem_flg = 0;

    pid = fork();

    if (pid == -1)
    {
        perror("fork");
        exit(EXIT_FAILURE);
    }
    else if (pid == 0)
    {
        shmid = shmget(key, SHMSIZE, IPC_CREAT | 0755);
        buff = shmat(shmid, NULL, 0);
        for (symbol = 'a'; symbol <= 'z'; symbol++)
        {
            int i = (rand() % (20000 - 1000 + 1)) + 1000;
            int j = (rand() % (20000 - 1000 + 1)) + 1000;
            semop(semid, &popProduce, 1);
            usleep(i);
            *buff = symbol;
            usleep(j);
            semop(semid, &vopConsume, 1);
        }
        shmdt(buff);
    }
    else if (pid > 0)
    {
        int i;
        shmid = shmget(key, SHMSIZE, IPC_CREAT | 0755);
        buff = shmat(shmid, 0, 0);
        for (i = 0; i <= 'z' - 'a'; i++)
        {
            int i = (rand() % (20000 - 1000 + 1)) + 1000;
            int j = (rand() % (20000 - 1000 + 1)) + 1000;
            semop(semid, &popConsume, 1);
            usleep(i);
            symbol = *buff;
            printf("Received symbol: %c\n", symbol);
            usleep(j);
            semop(semid, &vopProduce, 1);
        }
        shmdt(buff);
        wait(NULL);
        shmctl(shmid, IPC_RMID, NULL);
        semctl(semid, 0, IPC_RMID, NULL);
    }
    return 0;
}