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GRAPHEME_DECODE_UTF8

Section: C Library Functions (3)
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NAME

grapheme_decode_utf8 - decode first codepoint in UTF-8-encoded string

SYNOPSIS

In grapheme.h Ft size_t Fn grapheme_decode_utf8 const char *str size_t len uint_least32_t *cp

DESCRIPTION

The Fn grapheme_decode_utf8 function decodes the first codepoint in the UTF-8-encoded string str of length len If the UTF-8-sequence is invalid (overlong encoding, unexpected byte, string ends unexpectedly, empty string, etc.) the decoding is stopped at the last processed byte and the decoded codepoint set to GRAPHEME_INVALID_CODEPOINT

If cp is not NULL the decoded codepoint is stored in the memory pointed to by cp

Given NUL has a unique 1 byte representation, it is safe to operate on NUL-terminated strings by setting len to SIZE_MAX (stdint.h is already included by grapheme.h) and terminating when cp is 0 (see Sx EXAMPLES for an example).

RETURN VALUES

The Fn grapheme_decode_utf8 function returns the number of processed bytes and 0 if str is NULL or len is 0. If the string ends unexpectedly in a multibyte sequence, the desired length (that is larger than len is returned.

EXAMPLES

/* cc (-static) -o example example.c -lgrapheme */
#include <grapheme.h>
#include <inttypes.h>
#include <stdio.h>

void
print_cps(const char *str, size_t len)
{
        size_t ret, off;
        uint_least32_t cp;

        for (off = 0; off < len; off += ret) {
                if ((ret = grapheme_decode_utf8(str + off,
                                                len - off, &cp)) > (len - off)) {
                        /*
                         * string ended unexpectedly in the middle of a
                         * multibyte sequence and we have the choice
                         * here to possibly expand str by ret - len + off
                         * bytes to get a full sequence, but we just
                         * bail out in this case.
                         */
                        break;
                }
                printf("%"PRIxLEAST32"\n", cp);
        }
}

void
print_cps_nul_terminated(const char *str)
{
        size_t ret, off;
        uint_least32_t cp;

        for (off = 0; (ret = grapheme_decode_utf8(str + off,
                                                  SIZE_MAX, &cp)) > 0 &&
             cp != 0; off += ret) {
                printf("%"PRIxLEAST32"\n", cp);
        }
}

AUTHORS

An Laslo Hunhold Aq Mt dev@frign.de

This document was created by man2html, using the manual pages.
Time: 06:27:21 GMT, December 21, 2024