You can convert multibyte characters one at a time to wide characters with the mbtowc function. The wctomb function does the reverse. These functions are declared in `stdlib.h'.
mbtowc (``multibyte to wide character'') function when called with non-null string converts the first multibyte character beginning at string to its corresponding wide character code. It stores the result in *result .
mbtowc never examines more than size bytes. (The idea is to supply for size the number of bytes of data you have in hand.)
mbtowc with non-null string distinguishes three possibilities: the first size bytes at string start with valid multibyte character, they start with an invalid byte sequence or just part of a character, or string points to an empty string (a null character).
For a valid multibyte character, mbtowc converts it to a wide character and stores that in *result , and returns the number of bytes in that character (always at least 1 , and never more than size).
For an invalid byte sequence, mbtowc returns -1 . For an empty string, it returns 0 , also storing 0 in *result .
If the multibyte character code uses shift characters, then mbtowc maintains and updates a shift state as it scans. If you call mbtowc with a null pointer for string, that initializes the shift state to its standard initial value. It also returns nonzero if the multibyte character code in use actually has a shift state. See Shift State.
wctomb (``wide character to multibyte'') function converts the wide character code wchar to its corresponding multibyte character sequence, and stores the result in bytes starting at string. At most MB_CUR_MAX characters are stored.
wctomb with non-null string distinguishes three possibilities for wchar: a valid wide character code (one that can be translated to a multibyte character), an invalid code, and 0 .
Given a valid code, wctomb converts it to a multibyte character, storing the bytes starting at string. Then it returns the number of bytes in that character (always at least 1 , and never more than MB_CUR_MAX ).
If wchar is an invalid wide character code, wctomb returns -1 . If wchar is 0 , it returns 0 , also storing 0 in *string .
If the multibyte character code uses shift characters, then wctomb maintains and updates a shift state as it scans. If you call wctomb with a null pointer for string, that initializes the shift state to its standard initial value. It also returns nonzero if the multibyte character code in use actually has a shift state. See Shift State.
Calling this function with a wchar argument of zero when string is not null has the side-effect of reinitializing the stored shift state as well as storing the multibyte character 0 and returning 0 .