7.20.7 Multibyte/wide character conversion functions

• 7.20.7.1 The mblen function
• 7.20.7.2 The mbtowc function
• 7.20.7.3 The wctomb function

1

The behavior of the multibyte character functions is affected by the LC_CTYPE category of the current locale. For a state-dependent encoding, each function is placed into its initial conversion state by a call for which its character pointer argument, s, is a null pointer. Subsequent calls with s as other than a null pointer cause the internal conversion state of the function to be altered as necessary. A call with s as a null pointer causes these functions to return a nonzero value if encodings have state dependency, and zero otherwise.[1] Changing the LC_CTYPE category causes the conversion state of these functions to be indeterminate.

Footnotes

[1]

If the locale employs special bytes to change the shift state, these bytes do not produce separate wide character codes, but are grouped with an adjacent multibyte character.