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	1 GRAPHEME\_DECODE\_UTF8(3) - Library Functions Manual
	2
	3 # NAME
	4
	5 grapheme\_decode\_utf8 - decode first codepoint in UTF-8-encoded str…
	6
	7 # SYNOPSIS
	8
	9 #include <grapheme.h>
	10
	11 size\_t
	12 grapheme\_decode\_utf8(const char \str, size\_t len, uint\_lea…
	13
	14 # DESCRIPTION
	15
	16 The
	17 grapheme\_decode\_utf8()
	18 function decodes the first codepoint in the UTF-8-encoded string
	19 str
	20 of length
	21 len.
	22 If the UTF-8-sequence is invalid (overlong encoding, unexpected byte,
	23 string ends unexpectedly, empty string, etc.) the decoding is stopped
	24 at the last processed byte and the decoded codepoint set to
	25 `GRAPHEME_INVALID_CODEPOINT`.
	26
	27 If
	28 cp
	29 is not
	30 `NULL`
	31 the decoded codepoint is stored in the memory pointed to by
	32 cp.
	33
	34 Given NUL has a unique 1 byte representation, it is safe to operate on
	35 NUL-terminated strings by setting
	36 len
	37 to
	38 `SIZE_MAX`
	39 (stdint.h is already included by grapheme.h) and terminating when
	40 cp
	41 is 0 (see
	42 EXAMPLES
	43 for an example).
	44
	45 # RETURN VALUES
	46
	47 The
	48 grapheme\_decode\_utf8()
	49 function returns the number of processed bytes and 0 if
	50 str
	51 is
	52 `NULL`
	53 or
	54 len
	55 is 0.
	56 If the string ends unexpectedly in a multibyte sequence, the desired
	57 length (that is larger than
	58 len)
	59 is returned.
	60
	61 # EXAMPLES
	62
	63 /* cc (-static) -o example example.c -lgrapheme */
	64 #include <grapheme.h>
	65 #include <inttypes.h>
	66 #include <stdio.h>
	67
	68 void
	69 print_cps(const char *str, size_t len)
	70 {
	71 size_t ret, off;
	72 uint_least32_t cp;
	73
	74 for (off = 0; off < len; off += ret) {
	75 if ((ret = grapheme_decode_utf8(str + off,
	76 len - off, &cp))…
	77 /*
	78 * string ended unexpectedly in the midd…
	79 * multibyte sequence and we have the ch…
	80 * here to possibly expand str by ret - …
	81 * bytes to get a full sequence, but we …
	82 * bail out in this case.
	83 */
	84 break;
	85 }
	86 printf("%"PRIxLEAST32"\n", cp);
	87 }
	88 }
	89
	90 void
	91 print_cps_nul_terminated(const char *str)
	92 {
	93 size_t ret, off;
	94 uint_least32_t cp;
	95
	96 for (off = 0; (ret = grapheme_decode_utf8(str + off,
	97 SIZE_MAX, &cp)…
	98 cp != 0; off += ret) {
	99 printf("%"PRIxLEAST32"\n", cp);
	100 }
	101 }
	102
	103 # SEE ALSO
	104
	105 grapheme\_encode\_utf8(3),
	106 libgrapheme(7)
	107
	108 # AUTHORS
	109
	110 Laslo Hunhold ([[email protected]](mailto:[email protected]))
	111
	112 suckless.org - 2022-10-06