wcsncmp

int wcsncmp( const wchar_t* lhs, const wchar_t* rhs, size_t count );

Compares at most count wide characters of two null-terminated wide strings. The comparison is done lexicographically.

The sign of the result is the sign of the difference between the values of the first pair of wide characters that differ in the strings being compared.

The behavior is undefined if lhs or rhs are not pointers to null-terminated strings.

Parameters

Return value

Negative value if lhs appears before rhs in lexicographical order.

Zero if lhs and rhs compare equal.

Positive value if lhs appears after rhs in lexicographical order.

Notes

This function is not locale-sensitive, unlike wcscoll and wcsxfrm.

Example

#include <stdio.h>
#include <wchar.h>
#include <locale.h>
 
void demo(const wchar_t *lhs, const wchar_t *rhs, int sz)
{
    int rc = wcsncmp(lhs, rhs, sz);
    if(rc == 0)
        printf("First %d characters of [%ls] equal [%ls]\n", sz, lhs, rhs);
    else if(rc < 0)
        printf("First %d characters of [%ls] precede [%ls]\n", sz, lhs, rhs);
    else if(rc > 0)
        printf("First %d characters of [%ls] follow [%ls]\n", sz, lhs, rhs);
}
 
int main(void)
{
    const wchar_t *str1 = L"안녕하세요";
    const wchar_t *str2 = L"안녕히 가십시오";
 
    setlocale(LC_ALL, "en_US.utf8");
    demo(str1, str2, 5);
    demo(str2, str1, 8);
    demo(str1, str2, 2);
}

First 5 characters of [안녕하세요] precede [안녕히 가십시오]
First 8 characters of [안녕히 가십시오] follow [안녕하세요]
First 2 characters of [안녕하세요] equal [안녕히 가십시오]

References

• C11 standard (ISO/IEC 9899:2011):
• 7.29.4.4.3 The wcsncmp function (p: 434)
• C99 standard (ISO/IEC 9899:1999):
• 7.24.4.4.3 The wcsncmp function (p: 380)

See also