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× C Standard Library


The C <wchar.h> wcsncmp() function is used to compare up to num wide characters of two null-terminated wide strings lexicographically. The function starts comparing the first pair of wide characters of each wide string and continues comparing until the pair of wide characters are different in specified number of comparisons or until a terminating null wide character is reached.

Syntax

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

Parameters

lhs Specify pointer to the first null-terminated wide string to compare.
rhs Specify pointer to the second null-terminated wide string to compare.
num Specify maximum number of wide characters to compare.
size_t is an unsigned integer type.

Return Value

Based on the value of lhs and rhs, the function returns the following:

  • 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.

Example: Value returned by function = 0

The below example shows the usage of wcsncmp() function.

#include <stdio.h>
#include <wchar.h>
 
int main (){
  wchar_t str1[20] = L"Hello World!";
  wchar_t str2[20] = L"Hello";
  
  //comparing first 5 wide characters 
  //of str1 and str2
  int retval = wcsncmp(str1, str2, 5);

  //displaying the result
  if(retval != 0)
    printf("First 5 wide characters of str1 and str2 are not equal.\n");
  else
    printf("First 5 wide characters of str1 and str2 are equal.\n");
 
  printf("Value returned by the function: %d\n", retval);

  return 0;
}

The output of the above code will be:

First 5 wide characters of str1 and str2 are equal.
Value returned by the function: 0

Example: Value returned by function < 0

Lets consider this example where the returned value is less than zero.

#include <stdio.h>
#include <wchar.h>
 
int main (){
  wchar_t str1[20] = L"Hello";
  wchar_t str2[20] = L"World";
  
  //comparing first 3 wide characters 
  //of str1 and str2
  int retval = wcsncmp(str1, str2, 3);

  //displaying the result
  if(retval != 0)
    printf("First 3 wide characters of str1 and str2 are not equal.\n");
  else
    printf("First 3 wide characters of str1 and str2 are equal.\n");

  printf("Value returned by the function: %d\n", retval);

  return 0;
}

The output of the above code will be:

First 3 wide characters of str1 and str2 are not equal.
Value returned by the function: -1

Example: Value returned by function > 0

Lets consider another example where the returned value is greater than zero.

#include <stdio.h>
#include <wchar.h>
 
int main (){
  wchar_t str1[20] = L"Hello";
  wchar_t str2[20] = L"Apple";
  
  //comparing first 3 wide characters 
  //of str1 and str2
  int retval = wcsncmp(str1, str2, 3);

  //displaying the result
  if(retval != 0)
    printf("First 3 wide characters of str1 and str2 are not equal.\n");
  else
    printf("First 3 wide characters of str1 and str2 are equal.\n");

  printf("Value returned by the function: %d\n", retval);

  return 0;
}

The output of the above code will be:

First 3 wide characters of str1 and str2 are not equal.
Value returned by the function: 1

❮ C <wchar.h> Library