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The GNU C Library

6.3 Restartable Multibyte Conversion Functions

The ISO C standard defines functions to convert strings from a multibyte representation to wide character strings. There are a number of peculiarities:

• The character set assumed for the multibyte encoding is not specified as an argument to the functions. Instead the character set specified by the LC_CTYPE category of the current locale is used; see 7.3 Categories of Activities that Locales Affect.

• The functions handling more than one character at a time require NUL terminated strings as the argument (i.e., converting blocks of text does not work unless one can add a NUL byte at an appropriate place). The GNU C library contains some extensions to the standard that allow specifying a size, but basically they also expect terminated strings.

Despite these limitations the ISO C functions can be used in many contexts. In graphical user interfaces, for instance, it is not uncommon to have functions that require text to be displayed in a wide character string if the text is not simple ASCII. The text itself might come from a file with translations and the user should decide about the current locale, which determines the translation and therefore also the external encoding used. In such a situation (and many others) the functions described here are perfect. If more freedom while performing the conversion is necessary take a look at the iconv functions (see section 6.5 Generic Charset Conversion).

6.3.1 Selecting the conversion and its properties
6.3.2 Representing the state of the conversion
6.3.3 Converting Single Characters
6.3.4 Converting Multibyte and Wide Character Strings
6.3.5 A Complete Multibyte Conversion Example