Programming

Using Low-Level File I/O Functions

MATLAB includes a set of low-level file I/O functions that are based on the I/O functions of the ANSI Standard C Library. If you know C, you are probably familiar with these routines. This section covers

• Opening Files
• Reading Binary Data
• Writing Binary Data
• Controlling Position in a File
• Reading Strings Line by Line from Text Files
• Reading Formatted ASCII Data
• Writing Formatted Text Files
• Closing a File

The MATLAB file I/O functions use the same programming model as the C language routines. To read or write data, you perform these steps:

1. Open the file, using fopen. fopen returns a file identifier that you use with all the other low-level file I/O routines.
2. Operate on the file.
1. Read binary data, using fread.
2. Write binary data, using fwrite.
3. Read text strings from a file line-by-line, using fgets/fgetl.
4. Read formatted ASCII data, using fscanf.
5. Write formatted ASCII data, using fprintf.
3. Close the file, using fclose.

This section also describes how these functions affect the current position in the file where read or write operations happen and how you can change the position in the file.

Note    While the MATLAB file I/O commands are modeled on the C language I/O routines, in some ways their behavior is different. For example, the fread function is vectorized; that is, it continues reading until it encounters a text string or the end of file. These sections, and the MATLAB reference pages for these functions, highlight any differences in behavior.

Using the MATLAB HDF Utility API

Opening Files

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