Compares not more than maxchar characters of two ASCII character
    strings and returns a negative, 0, or positive integer,
    indicating that the ASCII values of the individual characters
    in the first string are less than, equal to, or greater than the
    values in the second string.

    Format

      #include  <string.h>

      int strncmp  (const char *str_1, const char *str_2, size_t
                   maxchar);

1 - Arguments

 str_1, str_2

    Pointers to character strings.

 maxchar

    The maximum number of characters (beginning with the first) to
    search in both str_1 and str_2. If maxchar is 0, no comparison is
    performed and 0 is returned (the strings are considered equal).

2 - Description

    The strncmp function compares no more than maxchar characters
    from the string pointed to by str_1 to the string pointed
    to by str_2. The strings are compared until a null character
    is encountered, the strings differ, or maxchar is reached.
    Characters that follow a difference or a null character are not
    compared.

3 - Return Values

    < 0                Indicates that str_1 is less than str_2.
    > 0                Indicates that str_1 is greater than str_2.

4 - Examples

    1.#include <string.h>

      #include <stdio.h>

      main()
      {
          printf( "%d\n", strncmp("abcde", "abc", 3));
      }

      When linked and executed, this example returns 0, because the
      first 3 characters of the 2 strings are equal:

        $ run tmp
        0

    2.#include <string.h>

      #include <stdio.h>

          main()
          {
              printf( "%d\n", strncmp("abcde", "abc", 4));
          }

      When linked and executed, this example returns a value greater
      than 0 because the first 4 characters of the 2 strings are not
      equal (The "d" in the first string is not equal to the null
      character in the second):

        $ run tmp
                100