MATLAB COMPILER RELEASE NOTES User's Guide download pdf (Page 650)

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Changes to Character Encoding in File I/O

The fopen function has a new optional argument, a string that specifies a name or alias

for the character encoding scheme associated with the file. If this argument is omitted

or is the empty string (''), the MATLAB default encoding scheme is used. Given a file

identifier as the only argument, fopen now returns an additional output value, a string

that identifies the character encoding scheme associated with the file.

Low-level file I/O functions that read data from files, including fread, fscanf, fgetl, and

fgets, read characters using the encoding scheme associated with the file during the call

to fopen. Low-level file I/O functions that write data, including fwrite and fprintf, write

characters using the encoding scheme associated with the file during the call to fopen.

Support for character encoding schemes has these limitations:

• Surrogate pairs are not supported. Each surrogate pair is read as a replacement

character, the equivalent of char(26).

• Stateful character encoding schemes are not supported.

• Byte order marks are not interpreted in any special way. Your code must skip them if

necessary.

• Scanning numbers, using fscanf, is supported only for character encoding schemes

that are supersets of ASCII. (Most popular character encoding schemes, with the

exception of UTF-16, are such supersets.)

Compatibility Considerations

In V7.1 (R14SP3), low-level file I/O functions that read and write data treated

characters as unsigned bytes. Programs using such functions as fread may have called

native2unicode to convert input to MATLAB characters using a particular encoding

scheme. Programs using such functions as fwrite may have called unicode2native to

convert output from MATLAB characters using a particular encoding scheme.

For example, on a Japanese Windows platform, where the default character encoding

scheme is Shift-JIS, a program may have used native2unicode and unicode2native

to read and write Japanese text in this way:

fid = fopen(file);

data = fread(fid, '*char')';

fclose(fid);

dataU = native2unicode(data);

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