IPC消息队列。 msgrcv 系统调用。系统五、如何跳出循环
我有一个消息队列，我从中循环获取消息。问题是我不知道如何退出循环。 msgrcv 返回 size_t 类型，因此它会继续运行。我应该比较返回值的什么值才能退出循环？
while(msgrcv(msqid, &msgreceived, sizeof(msgreceived), BUFFER_CHANGED, 0) != -1){
printf("%d %d %d %d ",msgreceived.value0,msgreceived.value1,msgreceived.value2,msgreceived.value3);
I have a message queue from which I am getting messages in a loop. The problem is that I don't know how to exit the loop. msgrcv returns type size_t so it keeps going. What value should I compare the return value so I can exit the loop?
while(msgrcv(msqid, &msgreceived, sizeof(msgreceived), BUFFER_CHANGED, 0) != -1){
printf("%d %d %d %d ",msgreceived.value0,msgreceived.value1,msgreceived.value2,msgreceived.value3);
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由于您的最后一个参数不包含
IPC_NOWAIT，因此msgrcv在等待未来消息时会阻塞。如果没有立即读取的消息，
msgrcv(..., ... | IPC_NOWAIT)将返回(size_t)-1并设置errno = ENOMSG。Because your last parameter does not include
IPC_NOWAIT,msgrcvblocks while waiting for future messages.If there is no message to be read immediately,
msgrcv(..., ... | IPC_NOWAIT)will return(size_t)-1and seterrno = ENOMSG.