共享内存shm*（生产者和消费者）

//heads.h
#ifndef HEAD_H
#define HEAD_H
#include <iostream>
#include <sys/shm.h> //share momery
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "shm_com.h"
#endif // HEAD_H

shm_com.h

#ifndef SHM_COM
#define SHM_COM

#define TEXT_SZ 2048
struct shared_use_st{
    int written_by_you;
    char some_text[TEXT_SZ];
};

#endif // SHM_COM

consumer.cpp

#include "headers.h"
using namespace std;
//consumer
int main()
{
    int running = 1;
    void *shared_memory = (void *)0;
    struct shared_use_st *shared_stuff;
    int shmid;
    
    srand((unsigned int)getpid());
    
    shmid = shmget((key_t)1234, sizeof(struct shared_use_st),0666|IPC_CREAT);
    
    if(shmid == -1)
    {
        fprintf(stderr, "shmget failed\n");
        exit(EXIT_FAILURE);
    }
    
    //sec let sys select shm address,
    //thi SHM_RND or SHM_RDONLY
    shared_memory = shmat(shmid, (void *)0, 0);
    if(shared_memory == (void *)-1)
    {
        fprintf(stderr, "shmat failed\n");
        exit(EXIT_FAILURE);
    }
    
    printf("Memory attached at %X\n",(unsigned int)(long)shared_memory);
    
    shared_stuff = (struct shared_use_st *)shared_memory;
    shared_stuff->written_by_you = 0;

    while (running) {
        if (shared_stuff->written_by_you) {
            printf("You wrote: %s", shared_stuff->some_text);
            sleep(rand()%4);
            shared_stuff->written_by_you = 0;
            if (strncmp(shared_stuff->some_text, "end", 3) == 0) {
                running = 0;
            }
        }
    }
    
    //shm devide and rm
    if(shmdt(shared_memory) == -1){
        fprintf(stderr, "shmdt failed\n");
        exit(EXIT_FAILURE);
    }
    
    if(shmctl(shmid, IPC_RMID, 0) == -1){
        fprintf(stderr, "shctl(IPC_RMID) failed \n");
        exit(EXIT_FAILURE);
    }

    exit(EXIT_SUCCESS);
}

producer.cpp

#include "headers.h"
using namespace std;
//producer
int main()
{
    int running = 1;
    void *shared_memory = (void *)0;
    struct shared_use_st *shared_stuff;
    char buffer[BUFSIZ];
    int shmid;

    shmid = shmget((key_t)1234, sizeof(struct shared_use_st), 0666|IPC_CREAT);
    //
    if (shmid == -1) {
        fprintf(stderr, "shmget failed\n");
        exit(EXIT_FAILURE);
    }

    shared_memory =shmat(shmid, (void *)0, 0);

    if(shared_memory == (void *)-1){
        fprintf(stderr, "shmat failed\n");
        exit(EXIT_FAILURE);
    }

    printf("memory attached at %X\n", (unsigned int)(long)shared_memory);

    shared_stuff = (struct shared_use_st *)shared_memory;

    while (running) {
        while (shared_stuff->written_by_you == 1) {
            sleep(1);
            printf("waiting for client...\n");
        }

        printf("Enter some text: ");
        fgets(buffer, BUFSIZ, stdin);

        strncpy(shared_stuff->some_text, buffer, TEXT_SZ);
        shared_stuff->written_by_you = 1;

        if(strncmp(buffer, "end", 3) == 0){
            running = 0;
        }
    }

    if(shmdt(shared_memory) == -1){
        fprintf(stderr, "shmdt failed\n");
        exit(EXIT_FAILURE);
    }
    return 0;
}

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