InternetQueryDataAvailable

This function queries the amount of data available.

At a Glance

Syntax

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

Parameters

hFile

Valid Internet file handle, as returned by InternetOpenUrl, FtpOpenFile, or HttpOpenRequest.

lpdwNumberOfBytesAvailable

Optional. Long pointer to a variable that receives the number of available bytes.

dwFlags

Reserved; set to zero.

dwContext

Reserved; 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.

Windows CE Remarks

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

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

Remarks

This function 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.