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strncmp, wcsncmp, _mbsncmp

Compare characters of two strings.

int strncmp(
   const char *string1,
   const char *string2,
   size_t count 
);
int wcsncmp(
   const wchar_t *string1,
   const wchar_t *string2,
   size_t count 
);
int _mbsncmp(
   const unsigned char *string1,
   const unsigned char string2,
   size_t count 
);

Parameters

string1, string2
Strings to compare.
count
Number of characters to compare.

Return Value

The return value indicates the relation of the substrings of string1 and string2 as follows.

Return value Description
< 0 string1 substring less than string2 substring
0 string1 substring identical to string2 substring
> 0 string1 substring greater than string2 substring

On an error, _mbsncmp returns _NLSCMPERROR, which is defined in STRING.H and MBSTRING.H.

Remarks

The strncmp function lexicographically compares, at most, the first count characters in string1 and string2 and returns a value indicating the relationship between the substrings. strncmp is a case-sensitive version of _strnicmp. Unlike strcoll, strncmp is not affected by locale. For more information on the LC_COLLATE category, see setlocale.

wcsncmp and _mbsncmp are wide-character and multibyte-character versions of strncmp. The arguments and return value of wcsncmp are wide-character strings; those of _mbsncmp are multibyte-character strings. _mbsncmp recognizes multibyte-character sequences according to the current multibyte code page and returns _NLSCMPERROR on an error. For more information, see Code Pages. These three functions behave identically otherwise. wcsncmp and _mbsncmp are case-sensitive versions of _wcsnicmp and _mbsnicmp.

Generic-Text Routine Mappings

TCHAR.H routine _UNICODE & _MBCS not defined _MBCS defined _UNICODE defined
_tcsnccmp strncmp _mbsnbcmp wcsncmp
_tcsncmp strncmp _mbsnbcmp wcsncmp
_tccmp Maps to macro or inline function _mbsncmp Maps to macro or inline function

Requirements

Routine Required header Compatibility
strncmp <string.h> ANSI, Win 98, Win Me, Win NT, Win 2000, Win XP
wcsncmp <string.h> or <wchar.h> ANSI, Win 98, Win Me, Win NT, Win 2000, Win XP
_mbsncmp <mbstring.h> Win 98, Win Me, Win NT, Win 2000, Win XP

For additional compatibility information, see Compatibility in the Introduction.

Libraries

All versions of the C run-time libraries.

Example

// crt_strncmp.c
#include <string.h>
#include <stdio.h>

char string1[] = "The quick brown dog jumps over the lazy fox";
char string2[] = "The QUICK brown fox jumps over the lazy dog";

int main( void )
{
   char tmp[20];
   int result;
   printf( "Compare strings:\n      %s\n      %s\n\n", string1, string2 );
   printf( "Function:   strncmp (first 10 characters only)\n" );
   result = strncmp( string1, string2 , 10 );
   if( result > 0 )
      strcpy( tmp, "greater than" );
   else if( result < 0 )
      strcpy( tmp, "less than" );
   else
      strcpy( tmp, "equal to" );
   printf( "Result:      String 1 is %s string 2\n\n", tmp );
   printf( "Function:   strnicmp _strnicmp (first 10 characters only)\n" );
   result = _strnicmp( string1, string2, 10 );
   if( result > 0 )
      strcpy( tmp, "greater than" );
   else if( result < 0 )
      strcpy( tmp, "less than" );
   else
      strcpy( tmp, "equal to" );
   printf( "Result:      String 1 is %s string 2\n", tmp );
}

Output

Compare strings:
      The quick brown dog jumps over the lazy fox
      The QUICK brown fox jumps over the lazy dog

Function:   strncmp (first 10 characters only)
Result:      String 1 is greater than string 2

Function:   strnicmp _strnicmp (first 10 characters only)
Result:      String 1 is equal to string 2

See Also

String Manipulation Routines | _mbsnbcmp | _mbsnbicmp | strcmp | strcoll Functions | _strnicmp | strrchr | _strset | strspn | Run-Time Routines and .NET Framework Equivalents

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