strcoll

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 <stdio.h>
#include <string.h>
#include <locale.h>
 
int main(void)
{
    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

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

Language
headers
Type support
Dynamic memory management
Error handling
Program utilities
Variadic function support
Date and time utilities
Strings library
Algorithms
Numerics
Input/output support
Localization support
Thread support (C11)
Atomic operations (C11)
Technical Specifications

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