strncmp -- Compare Strings

Format

#include <string.h>
int strncmp(const char *string1, const char *string2, size_t count);

Language Level: ANSI, POSIX, XPG4

On both OS/2 and Windows, strncmp compares the first count characters of string1 and string2. If count is greater than the length of string1 or string2, characters that follow a null character are not compared.

Return Value
strncmp returns a value indicating the relationship between the substrings, as follows:

Value Meaning
Less than 0 substring1 less than substring2
0 substring1 equivalent to substring2
Greater than 0 substring1 greater than substring2

Example
This example demonstrates the difference between strcmp and strncmp.

#include <stdio.h>
#include <string.h>
#define SIZE 10
int main(void)
{
  int  result;
  int  index = 3;
  char buffer1[SIZE] = "abcdefg";
  char buffer2[SIZE] = "abcfg";
  void print_result( int, char *, char * );
  result = strcmp( buffer1, buffer2 );
  printf( "Comparison of each character\n" );
  printf( "  strcmp: " );
  print_result( result, buffer1, buffer2 );
  result = strncmp( buffer1, buffer2, index);
  printf( "\nComparison of only the first %i characters\n", index );
  printf( "  strncmp: " );
  print_result( result, buffer1, buffer2 );
  return 0;
  /***************************************************************
     The output should be:
     Comparison of each character
        strcmp: "abcdefg" is less than "abcfg"
     Comparison of only the first 3 characters
        strncmp: "abcdefg" is identical to "abcfg"
  ***************************************************************/
}
void print_result( int res, char * p_buffer1, char * p_buffer2 )
{
  if ( res == 0 )
    printf( "\"%s\" is identical to \"%s\"\n", p_buffer1, p_buffer2);
  else if ( res < 0 )
    printf( "\"%s\" is less than \"%s\"\n", p_buffer1, p_buffer2 );
  else
    printf( "\"%s\" is greater than \"%s\"\n", p_buffer1, p_buffer2 );
}


strcmp -- Compare String
strcmpi -- Compare Strings Without Case Sensitivity
strcspn -- Compare Strings for Substrings
stricmp -- Compare Strings as Lowercase
strncat -- Concatenate Strings
strncpy -- Copy Strings
strnicmp -- Compare Strings Without Case Sensitivity
strpbrk -- Find Characters in String
strrchr -- Find Last Occurrence of Character in String
strspn -- Search Strings
wcscmp -- Compare Wide-Character Strings
wcsncmp -- Compare Wide-Character Strings
<string.h>