Hello! 
I hope someone can help me out. I need to write a code with 2 producers, one consumer and one shared buffer. The two producers should produce each 5 items (generate numbers) and the buffer will be full (10 numbers). After that, the consumer should "consume" them all.
This code is with threads, but now I should write that with processes instead of threads. Can someone help me out? 
My code for threads (P.S. these weird "?" symbols are just spaces in notepad :)):

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include </usr/include/semaphore.h>

// for sleep
#include <unistd.h>

#define BUFF_SIZE   5           /* total number of slots */
#define NP          3           /* total number of producers */
#define NC          3           /* total number of consumers */
#define NITERS      4           /* number of items produced/consumed */

typedef struct
{
    int buf[BUFF_SIZE];   /* shared var */
    int in;               /* buf[in%BUFF_SIZE] is the first empty slot */
    int out;              /* buf[out%BUFF_SIZE] is the first full slot */
    sem_t full;           /* keep track of the number of full spots */
    sem_t empty;          /* keep track of the number of empty spots */

    // use correct type here
    pthread_mutex_t mutex;          /* enforce mutual exclusion to shared data */
} sbuf_t;

sbuf_t shared;


void *Producer(void *arg)
{
    int i, item, index;

    index = (int)arg;


    for (i=0; i < NITERS; i++)
    {

        /* Produce item */
        item = i;

        /* Prepare to write item to buf */

        /* If there are no empty slots, wait */
        sem_wait(&shared.empty);
        /* If another thread uses the buffer, wait */
        pthread_mutex_lock(&shared.mutex);
        shared.buf[shared.in] = item;
        shared.in = (shared.in+1)%BUFF_SIZE;
        printf("[P%d] Producing %d ...\n", index, item);
        fflush(stdout);
        /* Release the buffer */
        pthread_mutex_unlock(&shared.mutex);
        /* Increment the number of full slots */
        sem_post(&shared.full);

        /* Interleave  producer and consumer execution */
        if (i % 2 == 1) sleep(1);
    }
    return NULL;
}

void *Consumer(void *arg)
{
    int i, item, index;

    index = (int)arg;
    for (i=NITERS; i > 0; i--) {
        sem_wait(&shared.full);
        pthread_mutex_lock(&shared.mutex);
        item=i;
        item=shared.buf[shared.out];
        shared.out = (shared.out+1)%BUFF_SIZE;
        printf("[C%d] Consuming  %d ...\n", index, item);
        fflush(stdout);
        /* Release the buffer */
        pthread_mutex_unlock(&shared.mutex);
        /* Increment the number of full slots */
        sem_post(&shared.empty);

        /* Interleave  producer and consumer execution */
        if (i % 2 == 1) sleep(1);
    }
    return NULL;
}

int main()
{
    pthread_t idP, idC;
    int index;

    sem_init(&shared.full, 0, 0);
    sem_init(&shared.empty, 0, BUFF_SIZE);
    pthread_mutex_init(&shared.mutex, NULL);
    for (index = 0; index < NP; index++)
    {
        /* Create a new producer */
        pthread_create(&idP, NULL, Producer, (void*)index);
    }
    /*create a new Consumer*/
    for(index=0; index<NC; index++)
    {
        pthread_create(&idC, NULL, Consumer, (void*)index);
    }

    pthread_exit(NULL);
}

Can someone, please, rewrite this without threads, but with processes (2 producers and one consumer). :D