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MBRLEN (3) | C library functions | Unix Manual Pages | :man

NAME

mbrlen - "get number of bytes in a character (restartable)"

CONTENTS

Library
Synopsis
Description
Return Values
Examples
Errors
See Also
Standards

LIBRARY


.Lb libc

SYNOPSIS


.In wchar.h size_t mbrlen "const char * restrict s" "size_t n" "mbstate_t * restrict ps"

DESCRIPTION

The mbrlen function inspects at most n bytes pointed to by s to determine the number of bytes needed to complete the next multibyte character.

The
.Vt mbstate_t argument, ps, is used to keep track of the shift state. If it is NULL, mbrlen uses an internal, static
.Vt mbstate_t object, which is initialized to the initial conversion state at program startup.

It is equivalent to:

"mbrtowc(NULL, s, n, ps);"

Except that when ps is a NULL pointer, mbrlen uses its own static, internal
.Vt mbstate_t object to keep track of the shift state.

RETURN VALUES

The mbrlen functions returns:
0 The next n or fewer bytes represent the null wide character ("L’\0’").
>0 The next n or fewer bytes represent a valid character, mbrlen returns the number of bytes used to complete the multibyte character.
(Vt size_t-2)
The next n contribute to, but do not complete, a valid multibyte character sequence, and all n bytes have been processed.
(Vt size_t-1)
An encoding error has occurred. The next n or fewer bytes do not contribute to a valid multibyte character.

EXAMPLES

A function that calculates the number of characters in a multibyte character string:
size_t
nchars(const char *s)
{
size_t charlen, chars;
mbstate_t mbs;


chars = 0;
memset(&mbs, 0, sizeof(mbs));
while ((charlen = mbrlen(s, MB_CUR_MAX, &mbs)) != 0 &&
charlen != (size_t)-1 && charlen != (size_t)-2) {
s += charlen;
chars++;
}


return (chars);
}

ERRORS

The mbrlen function will fail if:
[EILSEQ]
An invalid multibyte sequence was detected.
[EINVAL]
The conversion state is invalid.

SEE ALSO

mblen(3), mbrtowc(3), multibyte(3)

STANDARDS


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