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
Locale Categories.
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 Generic Charset Conversion).
