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13.4 Case insensitive comparison

The following functions implement comparison that ignores differences in case and normalization.

— Function: uint8_t * u8_casefold (const uint8_t *s, size_t n, const char *iso639_language, uninorm_t nf, uint8_t *resultbuf, size_t *lengthp)
— Function: uint16_t * u16_casefold (const uint16_t *s, size_t n, const char *iso639_language, uninorm_t nf, uint16_t *resultbuf, size_t *lengthp)
— Function: uint32_t * u32_casefold (const uint32_t *s, size_t n, const char *iso639_language, uninorm_t nf, uint32_t *resultbuf, size_t *lengthp)

Returns the case folded string.

Comparing u8_casefold (s1) and u8_casefold (s2) with the u8_cmp2 function is equivalent to comparing s1 and s2 with u8_casecmp.

The nf argument identifies the normalization form to apply after the case-mapping. It can also be NULL, for no normalization.

— Function: uint8_t * u8_ct_casefold (const uint8_t *s, size_t n, casing_prefix_context_t prefix_context, casing_suffix_context_t suffix_context, const char *iso639_language, uninorm_t nf, uint8_t *resultbuf, size_t *lengthp)
— Function: uint16_t * u16_ct_casefold (const uint16_t *s, size_t n, casing_prefix_context_t prefix_context, casing_suffix_context_t suffix_context, const char *iso639_language, uninorm_t nf, uint16_t *resultbuf, size_t *lengthp)
— Function: uint32_t * u32_ct_casefold (const uint32_t *s, size_t n, casing_prefix_context_t prefix_context, casing_suffix_context_t suffix_context, const char *iso639_language, uninorm_t nf, uint32_t *resultbuf, size_t *lengthp)

Returns the case folded string. The case folding takes into account the case mapping contexts of the prefix and suffix strings.

— Function: int u8_casecmp (const uint8_t *s1, size_t n1, const uint8_t *s2, size_t n2, const char *iso639_language, uninorm_t nf, int *resultp)
— Function: int u16_casecmp (const uint16_t *s1, size_t n1, const uint16_t *s2, size_t n2, const char *iso639_language, uninorm_t nf, int *resultp)
— Function: int u32_casecmp (const uint32_t *s1, size_t n1, const uint32_t *s2, size_t n2, const char *iso639_language, uninorm_t nf, int *resultp)
— Function: int ulc_casecmp (const char *s1, size_t n1, const char *s2, size_t n2, const char *iso639_language, uninorm_t nf, int *resultp)

Compares s1 and s2, ignoring differences in case and normalization.

The nf argument identifies the normalization form to apply after the case-mapping. It can also be NULL, for no normalization.

If successful, sets *resultp to -1 if s1 < s2, 0 if s1 = s2, 1 if s1 > s2, and returns 0. Upon failure, returns -1 with errno set.

The following functions additionally take into account the sorting rules of the current locale.

— Function: char * u8_casexfrm (const uint8_t *s, size_t n, const char *iso639_language, uninorm_t nf, char *resultbuf, size_t *lengthp)
— Function: char * u16_casexfrm (const uint16_t *s, size_t n, const char *iso639_language, uninorm_t nf, char *resultbuf, size_t *lengthp)
— Function: char * u32_casexfrm (const uint32_t *s, size_t n, const char *iso639_language, uninorm_t nf, char *resultbuf, size_t *lengthp)
— Function: char * ulc_casexfrm (const char *s, size_t n, const char *iso639_language, uninorm_t nf, char *resultbuf, size_t *lengthp)

Converts the string s of length n to a NUL-terminated byte sequence, in such a way that comparing u8_casexfrm (s1) and u8_casexfrm (s2) with the gnulib function memcmp2 is equivalent to comparing s1 and s2 with u8_casecoll.

nf must be either UNINORM_NFC, UNINORM_NFKC, or NULL for no normalization.

— Function: int u8_casecoll (const uint8_t *s1, size_t n1, const uint8_t *s2, size_t n2, const char *iso639_language, uninorm_t nf, int *resultp)
— Function: int u16_casecoll (const uint16_t *s1, size_t n1, const uint16_t *s2, size_t n2, const char *iso639_language, uninorm_t nf, int *resultp)
— Function: int u32_casecoll (const uint32_t *s1, size_t n1, const uint32_t *s2, size_t n2, const char *iso639_language, uninorm_t nf, int *resultp)
— Function: int ulc_casecoll (const char *s1, size_t n1, const char *s2, size_t n2, const char *iso639_language, uninorm_t nf, int *resultp)

Compares s1 and s2, ignoring differences in case and normalization, using the collation rules of the current locale.

The nf argument identifies the normalization form to apply after the case-mapping. It must be either UNINORM_NFC or UNINORM_NFKC. It can also be NULL, for no normalization.

If successful, sets *resultp to -1 if s1 < s2, 0 if s1 = s2, 1 if s1 > s2, and returns 0. Upon failure, returns -1 with errno set.