ReadMsgQueue
A version of this page is also available for
4/8/2010
This function reads a single message from a message queue.
Syntax
BOOL ReadMsgQueue(
HANDLE hMsgQ,
LPVOID lpBuffer,
DWORD cbBufferSize,
LPDWORD lpNumberOfBytesRead,
DWORD dwTimeout,
DWORD* pdwFlags
);
Parameters
- hMsgQ
[in] Handle to an open message queue.
- lpBuffer
[out] Pointer to a buffer to store a read message. This parameter cannot be NULL.
- cbBufferSize
[in] Size of the buffer, in bytes, specified by lpBuffer. This parameter cannot be 0 (zero).
- lpNumberOfBytesRead
[out] Number of bytes stored in lpBuffer. This parameter cannot be NULL.
- dwTimeout
[in] Time in milliseconds (ms) before the read operation times out. If set to zero, the read operation will not block if there is no data to read. If set to INFINITE, the read operation will block until data is available or the status of the queue changes.
- pdwFlags
[out] Pointer to a DWORD to indicate the properties of the message. A value of MSGQUEUE_MSGALERT specifies that the message is an alert message.
Return Value
TRUE indicates success. FALSE indicates failure. To obtain extended error information, call GetLastError. The following table shows possible values returned by GetLastError.
| Value | Description |
|---|---|
ERROR_INSUFFICIENT_BUFFER |
The buffer specified by lpBuffer is too small to read a message. The read operation succeeded, but only cbBufferSize bytes of data were copied. |
ERROR_PIPE_NOT_CONNECTED |
No writers were attached to the message queue, and MSGQUEUE_ALLOW_BROKEN was not specified. All the writers exited while a reader was blocked, and MSGQUEUE_ALLOW_BROKEN was not specified. The read operation failed. |
ERROR_TIMEOUT |
The dwTimeout parameter was set to zero, and there was no data to read. |
Requirements
| Header | msgqueue.h |
| Library | coredll.lib |
| Windows Embedded CE | Windows CE .NET 4.0 and later |
| Windows Mobile | Windows Mobile Version 5.0 and later |
See Also
Reference
Message Queue Point-to-Point Functions
CloseMsgQueue
CreateMsgQueue
GetMsgQueueInfo
MSGQUEUEINFO
MSGQUEUEOPTIONS
OpenMsgQueue
ReadMsgQueue
WriteMsgQueue