External Interfaces

Writing Character Data

MATLAB writes character data to MAT-files using Unicode character encoding by default. You can override this setting and use the default character set for your system instead by doing one of the following:

• From the MATLAB command line or a MATLAB function, save your data to the MAT-file using the command save -nounicode
• From a C mex file, open the MAT-file you will write the data to using the command matOpen -wL

See the individual reference pages for these functions for more information.

You can override this setting for all of your MATLAB sessions using the Preferences dialog box. Open the Preferences dialog and select General and then MAT-Files. Click on Unicode or Local Character Set. See General Preferences for MATLAB in the Desktop Tools and Development Environment documentation for more information.

Note    Level 4 MAT files support only ASCII character data. If you have non-ASCII character data, writing a Level 4 MAT file is not officially supported. In the event that a Level 4 MAT file is created with such character data, it is unlikely that the original representation of the characters will be preserved.

Converting Character Data

Writing character data to MAT-files using Unicode encoding enables you to share data with users that have systems with a different default system character encoding scheme, without character data loss or corruption. Although conversion between Unicode and other encoding forms is often lossless, there are scenarios in which round-trip conversions can result in loss of data. The following guidelines may reduce your chances of data loss or corruption.

In order to prevent loss or corruption of character data, all users sharing the data must have at least one of the following in common:

• They exchange Unicode-based MAT-files, and use a version of MATLAB that supports these files.
• Their computer systems all use the same default character set, and all character data in the MAT-file was written using the -nounicode option

As an illustration, if one user on a Japanese language operating system writes ASCII data having more than 7 bits per character to a MAT-file, another user running MATLAB version 6.5 on an English language operating system will be unable to read the data accurately. However, if both had MATLAB version 7, then the information could be shared freely without loss of data or corruption.

Reading and Writing MAT-Files

Finding Associated Files

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