InternetQueryDataAvailable

  • 项目

This function queries the amount of data available.

BOOL WINAPI InternetQueryDataAvailable(
  HINTERNET hFile, 
  LPDWORD lpdwNumberOfBytesAvailable, 
  DWORD dwFlags, 
  DWORD dwContext
);

Parameters

  • hFile
    [in] Valid Internet file handle, as returned by InternetOpenUrl, FtpOpenFile, or HttpOpenRequest.
  • lpdwNumberOfBytesAvailable
    [out] Optional. Long pointer to a variable that receives the number of available bytes.
  • dwFlags
    [in] Reserved. Must be set to zero.
  • dwContext
    [in] Reserved. Must be set to zero.

Return Values

TRUE indicates success. FALSE indicates failure. To get extended error information, call GetLastError. If the function finds no matching files, GetLastError returns ERROR_NO_MORE_FILES.

Remarks

Windows CE stipulates that the hFile parameter must be a valid Internet file handle returned by the FtpOpenFile, FtpFindFirstFile, or HttpOpenRequest function.

The InternetQueryDataAvailable function can be completed in either synchronous or asynchronous mode.

InternetQueryDataAvailable returns the number of bytes of data that are available to be read immediately by a subsequent call to InternetReadFile. If there is currently no data available and the end of the file has not been reached, the request waits until data becomes available. The amount of data remaining will not be recalculated until all available data indicated by the call to InternetQueryDataAvailable is read.

For HINTERNET handles created by HttpOpenRequest and sent by HttpSendRequestEx, a call to HttpEndRequest must be made on the handle before InternetQueryDataAvailable can be used.

Requirements

OS Versions: Windows CE 2.0 and later.
Header: Wininet.h.
Link Library: Wininet.lib.

See Also

About HINTERNET Handles | FtpFindFirstFile | FtpOpenFile | HttpEndRequest | HttpOpenRequest | HttpSendRequestEx | InternetOpenUrl | InternetQueryDataAvailable | InternetReadFile | WinInet Functions

Last updated on Wednesday, April 13, 2005

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