关于QIODevice::bytesAvailable() 函数 [复制链接]

QIODevice::bytesAvailable()是这么说的：Returns the number of bytes
that are available for reading. This function is commonly used with sequential
devices to determine the number of bytes to allocate in a buffer beforereading.
有一个Qt的例子是这样的：
｛
uint time2u = 0;
QDataStream in(tcpSocket);
in.setVersion(QDataStream::Qt_4_3);
if(time2u==0)
   {
if(tcpSocket->bytesAvailable()<(int)sizeof(uint))  return;
  in>>time2u;
}
dateTimeEdit->setDateTime(QDateTime::fromTime_t(time2u));
getBtn->setEnabled(true);
｝我想问的是上面代码里if(tcpSocket->bytesAvailable()<(int)sizeof(uint))是什么意思？
按理说tcpSocket->bytesAvailable()要比较应该是读到的字节数，怎么会是(int)sizeof(uint)呢？

一次读4个字节输出给time2u，不足4个字节就不读，避免自己组织数据的麻烦。当然你要不嫌麻烦你也可以全部读出来自己移位。