u8_strcmp(3C) (man pages section 3: Basic Library Functions)

man pages section 3: Basic Library Functions

u8_strcmp(3C)

Name

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:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Interface Stability	Committed
MT-Level	MT-Safe