Using the basic I/O services is similar to using the run-time file I/O
services of the C run-time library. Files must be opened before they can be read or
written. After reading or writing, the file must be closed. You can also change
the current read or write location within an open file.
Before you begin any I/O operations to a file, you must open the file by using
function. This function returns a file handle of type HMMIO
. You can use this file handle to identify the open file when calling other
file I/O functions.
file handle is not a standard file handle. Do not use HMMIO
file handles with Win32 or C run-time file I/O functions.
When you use mmioOpen
to open a file, you use a flag to specify whether you are opening it for
reading, writing, or both. You can also specify flags that enable you to create or
delete a file. Use the mmioClose
function to close a file when you are finished reading or writing to it.
You can read and write files by using the mmioRead
functions respectively. The next read or write operation occurs at the
current file position or file pointer in a file. The current file position is
advanced each time a file is read or written.
You can also change the current file position by using the mmioSeek
function. You should ensure that you specify a valid location in a file. If
you specify an invalid location, such as past the end of the file, mmioSeek
may not return an error, but subsequent I/O operations could fail.
There are flags you can use with the mmioOpen
function for operations beyond basic file I/O. By specifying an MMIOINFO
structure, for example, you can open memory files, specify a custom I/O
procedure, or supply a buffer for buffered I/O.
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