Segmentation fault when get an array form shared memory-CodePudding

I want to share an array in shared memory but i can't fill it cause give me back segmentation fault and i have no idea why.This is the first time with shared memory so i don't know how to use it for my purpose.

int main(int argc, char const *argv[])
{
    int *array;
    int shmid;
    shmid = shmget(1234,3*sizeof(int),IPC_CREAT);
    if(shmid == -1) {
        perror("shmget error");
        exit(EXIT_FAILURE);
    }
    array = (int*)shmat(shmid,NULL,0);
    int array_copy[3];
    int i;
    for (i = 0; i < 3; i  ){
        array_copy[i] = i;
        memcpy( &array[i], &array_copy[i], sizeof(int) );
    }
    for (i = 0; i < 3; i  )
        printf("\n nm: %d and array: %d",array_copy[i],array[i]);
    shmdt((void *) array);
    return 0;
}

CodePudding user response：

You're not checking the result of shmat(). On my system it fails and perror() says "Permission denied". So you can look for answers here: c programming shmat ( ) permission denied