u8_strcmp

- UTF-8 string comparison function

Synopsis

#include <sys/u8_textprep.h>

int u8_strcmp(const char *s1, const char *s2, size_t n,
     int flag, size_t version, int *errnum);

Parameters

s1, s2

Pointers to null-terminated UTF-8 strings

n

The maximum number of bytes to be compared. If 0, the comparison is performed until either or both of the strings are examined to the string terminating null byte.

flag

The possible comparison options constructed by a bit-wise-inclusive-OR of the following values:

U8_STRCMP_CS

Perform case-sensitive string comparison. This is the default.

U8_STRCMP_CI_UPPER

Perform case-insensitive string comparison based on Unicode upper case converted results of s1 and s2.

U8_STRCMP_CI_LOWER

Perform case-insensitive string comparison based on Unicode lower case converted results of s1 and s2.

U8_STRCMP_NFD

Perform string comparison after s1 and s2 have been normalized by using Unicode Normalization Form D.

U8_STRCMP_NFC

Perform string comparison after s1 and s2 have been normalized by using Unicode Normalization Form C.

U8_STRCMP_NFKD

Perform string comparison after s1 and s2 have been normalized by using Unicode Normalization Form KD.

U8_STRCMP_NFKC

Perform string comparison after s1 and s2 have been normalized by using Unicode Normalization Form KC.

Only one case-sensitive or case-insensitive option is allowed. Only one Unicode Normalization option is allowed.

version

The version of Unicode data that should be used during comparison. The following values are supported:

U8_UNICODE_320

Use Unicode 3.2.0 data during comparison.

U8_UNICODE_500

Use Unicode 5.0.0 data during comparison.

U8_UNICODE_LATEST

Use the latest Unicode version data available, which is Unicode 5.0.0.

errnum

A non-zero value indicates that an error has occurred during comparison. The following values are supported:

EBADF

The specified option values are conflicting and cannot be supported.

EILSEQ

There was an illegal character at s1, s2, or both.

EINVAL

There was an incomplete character at s1, s2, or both.

ERANGE

The specified Unicode version value is not supported.

Description

The u8_stcmp() function internally processes UTF-8 strings pointed to by s1 and s2 based on the corresponding version of the Unicode Standard and other input arguments and compares the result strings in byte-by-byte, machine ordering.

When multiple comparison options are specified, Unicode Normalization is performed after case-sensitive or case-insensitive processing is performed.

Return Values

The u8_strcmp() function returns an integer greater than, equal to, or less than 0 if the string pointed to by s1 is greater than, equal to, or less than the string pointed to by s2, respectively.

When u8_strcmp() detects an illegal or incomplete character, such character causes the function to set errnum to indicate the error. Afterward, the comparison is still performed on the resultant strings and a value based on byte-by-byte comparison is always returned.

Examples

Example 1 Perform simple default string comparison.

#include <sys/u8_textprep.h>

int
docmp_default(const char *u1, const char *u2) {
    int result;
    int errnum;

    result = u8_strcmp(u1, u2, 0, 0, U8_UNICODE_LATEST, &errnum);
    if (errnum == EILSEQ)
        return (-1);
    if (errnum == EINVAL)
        return (-2);
    if (errnum == EBADF)
        return (-3);
    if (errnum == ERANGE)
        return (-4);

Example 2 Perform upper case based case-insensitive comparison with Unicode 3.2.0 date.

#include <sys/u8_textprep.h>

int
docmp_caseinsensitive_u320(const char *u1, const char *u2) {
    int result;
    int errnum;

    result = u8_strcmp(u1, u2, 0, U8_STRCMP_CI_UPPER,
        U8_UNICODE_320, &errnum);
    if (errnum == EILSEQ)
        return (-1);
    if (errnum == EINVAL)
        return (-2);
    if (errnum == EBADF)
        return (-3);
    if (errnum == ERANGE)
        return (-4);

    return (result);
}

Example 3 Perform Unicode Normalization Form D.

Perform Unicode Normalization Form D and upper case based case-insensitive comparison with Unicode 3.2.0 date.

#include <sys/u8_textprep.h>

int
docmp_nfd_caseinsensitive_u320(const char *u1, const char *u2) {
    int result;
    int errnum;

    result = u8_strcmp(u1, u2, 0,
        (U8_STRCMP_NFD|U8_STRCMP_CI_UPPER), U8_UNICODE_320,
        &errnum);
    if (errnum == EILSEQ)
        return (-1);
    if (errnum == EINVAL)
        return (-2);
    if (errnum == EBADF)
        return (-3);
    if (errnum == ERANGE)
        return (-4);

    return (result);
}

Attributes

See attributes(5) for descriptions of the following attributes:

See Also

u8_textprep_str(3C), u8_validate(3C), attributes(5), u8_strcmp(9F), u8_textprep_str(9F), u8_validate(9F)

The Unicode Standard