This function determines the length of a file. If the FileLen function is called for an open file, it returns the file length before it was opened. To determine the current file length of an open file, use the Lof function.
此函数确定文件的长度。如果调用 FileLen 函数来打开文件，此函数将在打开文件之前返回文件的长度。要确定已打开文件的当前文件长度，请使用 Lof 函数。