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 section 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 the standard which allow specifying a size but basically they also expect terminated strings.

Despite these limitations the ISO C functions can very well be used in many contexts. In graphical user interfaces, for instance, it is not uncommon to have functions which require text to be displayed in a wide character string if it 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 Generic Charset Conversion).

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