Parameters
hFile
[in] Handle to the file whose size is to be returned.
lpFileSizeHigh
[out] Pointer to the variable where the high-order word of the file size is returned. This parameter can be NULL if the application does not require the high-order word.
Return Values
If the function succeeds, the return value is the low-order doubleword of the file size, and, if lpFileSizeHigh is non-NULL, the function puts the high-order doubleword of the file size into the variable pointed to by that parameter.
If the function fails and lpFileSizeHigh is NULL, the return value is INVALID_FILE_SIZE. To get extended error information, call GetLastError.
If the function fails and lpFileSizeHigh is non-NULL, the return value is INVALID_FILE_SIZE and GetLastError will return a value other than NO_ERROR.
Remarks
You cannot use the GetFileSize function with a handle of a nonseeking device such as a pipe or a communications device. To determine the file type for hFile, use the GetFileType function.
The GetFileSize function retrieves the uncompressed size of a file. Use the GetCompressedFileSize function to obtain the compressed size of a file.
Note that if the return value is INVALID_FILE_SIZE, an application must call GetLastError to determine whether the function has succeeded or failed. The reason the function may appear to fail when it has not is that lpFileSizeHigh could be non-NULL or the file size could be 0xffffffff. In this case, GetLastError will return NO_ERROR upon success.
