linux c 共享内存

#include <stdio.h>
#include <stdlib.h>
#include <sys/ipc.h>
#include <sys/shm.h>

#define SHM_SIZE 1024

int main() {
    key_t key = ftok("/tmp/shmfile", 65);
    int shmid = shmget(key, SHM_SIZE, 0666|IPC_CREAT);
    if (shmid == -1) {
        perror("shmget");
        exit(1);
    }

    char *str = (char*) shmat(shmid, (void*)0, 0);
    if (str == (char*)(-1)) {
        perror("shmat");
        exit(1);
    }

    printf("Writing to shared memory: \"%s\"\n", "Hello, World!");
    strncpy(str, "Hello, World!", SHM_SIZE);

    shmdt(str);
    return 0;
}

#include <stdio.h>
#include <stdlib.h>
#include <sys/ipc.h>
#include <sys/shm.h>

#define SHM_SIZE 1024

int main() {
    key_t key = ftok("/tmp/shmfile", 65);
    int shmid = shmget(key, SHM_SIZE, 0666|IPC_CREAT);
    if (shmid == -1) {
        perror("shmget");
        exit(1);
    }

    char *str = (char*) shmat(shmid, (void*)0, 0);
    if (str == (char*)(-1)) {
        perror("shmat");
        exit(1);
    }

    printf("Reading from shared memory: \"%s\"\n", str);

    shmdt(str);
    shmctl(shmid, IPC_RMID, NULL);
    return 0;
}