strcoll

 

C

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Technical Specifications

Symbol index

 

Strings library

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Null-terminated byte strings

Functions
Character manipulation
isalnum isalpha islower isupper isdigit isxdigit isblank (C99)	iscntrl isgraph isspace isprint ispunct tolower toupper
Conversions to and from numeric formats
atoiatolatoll (C99) atof strtolstrtoll (C99) strtoulstrtoull (C99)	strtoimaxstrtoumax (C99)(C99) strtofstrtodstrtold (C99)(C99) strfromfstrfromdstrfroml (C23)(C23)(C23)
String manipulation
strcpystrcpy_s (C11) strncpystrncpy_s (C11) strcatstrcat_s (C11)	strncatstrncat_s (C11) strxfrm strdup (C23) strndup (C23)
String examination
strlenstrnlen_s (C11) strcmp strncmp strcoll strchr strrchr	strspn strcspn strpbrk strstr strtokstrtok_s (C11)
Memory manipulation
memchr memcmp memsetmemset_explicitmemset_s (C23)(C11)	memcpymemcpy_s (C11) memmovememmove_s (C11) memccpy (C23)
Miscellaneous
strerrorstrerror_sstrerrorlen_s (C11)(C11)

 

Defined in header <string.h>
int strcoll( const char* lhs, const char* rhs );

Compares two null-terminated byte strings according to the current locale as defined by the LC_COLLATE category.

Parameters

lhs, rhs

-

pointers to the null-terminated byte strings to compare

Return value

• Negative value if lhs is less than (precedes) rhs.
• ​0​ if lhs is equal to rhs.
• Positive value if lhs is greater than (follows) rhs.

Notes

Collation order is the dictionary order: the position of the letter in the national alphabet (its equivalence class) has higher priority than its case or variant. Within an equivalence class, lowercase characters collate before their uppercase equivalents and locale-specific order may apply to the characters with diacritics. In some locales, groups of characters compare as single collation units. For example, "ch" in Czech follows "h" and precedes "i", and "dzs" in Hungarian follows "dz" and precedes "g".

Example

Run this code

#include <locale.h>
#include <stdio.h>
#include <string.h>
 
int main(void)
{
    setlocale(LC_COLLATE, "cs_CZ.utf8");
    // Alternatively, ISO-8859-2 (a.k.a. Latin-2)
    // may also work on some OS:
    // setlocale(LC_COLLATE, "cs_CZ.iso88592");
 
    const char* s1 = "hrnec";
    const char* s2 = "chrt";
 
    printf("In the Czech locale: ");
    if (strcoll(s1, s2) < 0)
        printf("%s before %s\n", s1, s2);
    else
        printf("%s before %s\n", s2, s1);
 
    printf("In lexicographical comparison: ");
    if (strcmp(s1, s2) < 0)
        printf("%s before %s\n", s1, s2);
    else
        printf("%s before %s\n", s2, s1);
}

Output:

In the Czech locale: hrnec before chrt
In lexicographical comparison: chrt before hrnec

References

• C23 standard (ISO/IEC 9899:2024):

• 7.24.4.3 The strcoll function (p: TBD)

• C17 standard (ISO/IEC 9899:2018):

• 7.24.4.3 The strcoll function (p: TBD)

• C11 standard (ISO/IEC 9899:2011):

• 7.24.4.3 The strcoll function (p: 366)

• C99 standard (ISO/IEC 9899:1999):

• 7.21.4.3 The strcoll function (p: 329)

• C89/C90 standard (ISO/IEC 9899:1990):

• 4.11.4.3 The strcoll function

See also

wcscoll (C95)	compares two wide strings in accordance to the current locale (function)
strxfrm	transform a string so that strcmp would produce the same result as strcoll (function)
wcsxfrm (C95)	transform a wide string so that wcscmp would produce the same result as wcscoll (function)
strcmp	compares two strings (function)
C++ documentation for strcoll