mblen(3)                                                       mblen(3)

  mblen()

  NAME

    mblen() - get number of bytes in a character

  SYNOPSIS

    #include 

    int mblen (const char *s, size_t n)

  DESCRIPTION

    If s is not a null pointer, the mblen(3) function determines the umber of
    bytes constituting the character pointed to by s, Except that the shift
    state of mbtowc(3) is not affected, it is equivalent to:

    mbtowc((whcar_t *)0, s, n)

    The behavior of this function is affected by the LC_CTYPE category of the
    current locale. For a state-dependent encoding, this function is placed
    into its initial 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 state of the function to be altered as necessary. A
    call with s as a null pointer causes this function to return a non-zero
    value if encodings have state dependency, and 0 otherwise. If the
    implementation employs special bytes to change the shift state, these
    bytes do not produce separate wide-character codes, but are grouped with
    an adjacent character. Changing the LC_CTYPE category causes the shift
    state of this function to be indeterminate.

  RETURN VALUES

    If s is a null pointer, mblen(3) returns a non-zero or 0 value, if
    character encodings, respectively, do or do not have state-dependent
    encodings. If s is not a null pointer, mblen(3) either returns 0 (if s
    points to the null byte), or returns the number of bytes that constitute
    the character (if the next n or fewer bytes form a valid character), or
    returns -1 (if they do not form a valid character) and may set errno to
    indicate the error. In no case will the value returned be greater than n
    or the value of the MB_CUR_MAX macro.

  ERRORS

    The mblen(3) function may fail if:

    [EILSEQ]
        Invalid byte sequence is detected.

  SEE ALSO

    mbtowc(3)

    mbstowcs(3)

    wctomb(3)

    wcstombs(3)

  USAGE NOTES

    The mblen function is thread safe.

    The mblen function is not async-signal safe.