使用shmclt（）返回无效参数错误，从而在进程之间释放内存

Question

我在编程中创建了几个子进程，所以我决定 创建一个共享内存数组，如下所示：

void makeSharedArr(int sharedId, int ** sharedArr, int numArgs)
{

    sharedId = shmget(IPC_PRIVATE, numArgs*sizeof(int), 0666 );
    if (sharedId < 0) 
    {
        perror("error allocating shared memory...exiting\n");
        exit(ERROR);
    }
    else 
    {
        write(1,"allocated memory...\n",20);
    }
    *sharedArr = (int *) shmat(sharedId, NULL, 0);
    if((long) sharedArr == -1) 
    {
        perror("error attaching the shared memory...exiting\n");
        exit(ERROR);
    }
    else
   {
        write(1,"attached the shared memory...\n",30);
   }

 }

在我操作一些工作之后，共享阵列成功分离，但是我在删除父函数中的内存时遇到了问题：

 void parent(int *arr, int sharedId, int numArgs)
{
    //wait for all children
    while(wait(NULL) > 0) {/*..waiting..*/}

    // print array
    printf("array in parent: ");
    printArr(arr, numArgs);

    // detach and mark memory to be free 
    if(shmdt((void *) arr) == 0)
    {
        write(1, "memory block was detached...\n",29); 
    }
    else
    {
         write(1,"error detaching memory block...\n",32);
    }
    if(shmctl(sharedId, IPC_RMID, (struct shmid_ds *) NULL) == 0)
    {
         write(1, "memory block is now free...\n",28); 
    }
    else
    {  
        perror("error freeing memory\n");
        //write(1,"error freeing memory...\n",24);
    }
    // notify that parent is exiting
    printf("Parent exiting...\n");
 }