Concatenates a counted number of wide-characters from one string
    to another.

    Format

      #include  <wchar.h>

      wchar_t *wcsncat  (wchar_t *wstr_1, const wchar_t *wstr_2,

                        size_t maxchar);

1 - Function Variants

    This function also has variants named _wcsncat32 and _wcsncat64
    for use with 32-bit and 64-bit pointer sizes, respectively.

2 - Arguments

 wstr_1, wstr_2

    Pointers to null-terminated wide-character strings.

 maxchar

    The maximum number of wide characters from wstr_2 that are copied
    to wstr_1. If maxchar is 0, no characters are copied from wstr_2.

3 - Description

    This function appends wide characters from the wide-character
    string wstr_2 to the end of wstr_1, up to a maximum of maxchar
    characters. A terminating null wide character is always
    appended to the result of the wcsncat function. Therefore, the
    maximum number of wide characters that can end up in wstr_1 is
    wcslen(wstr_1) + maxchar + 1).

    See also wcscat.

4 - Return Values

    x                  The first argument, wstr_1, which is assumed
                       to be large enough to hold the concatenated
                       result.

5 - Example

        #include <stdlib.h>
        #include <stdio.h>
        #include <wchar.h>
        #include <string.h>

  /* This program concatenates two wide-character strings using  */
  /* the wcsncat function, and then manually compares the result */
  /* to the expected result                                      */

        #define S1LENGTH 10
        #define S2LENGTH 8
        #define SIZE     3

        main()
        {
            int i;
            wchar_t s1buf[S1LENGTH + S2LENGTH];
            wchar_t s2buf[S2LENGTH];
            wchar_t test1[S1LENGTH + S2LENGTH];

            /* Initialize the three wide-character strings */

         if (mbstowcs(s1buf, "abcmnexyz", S1LENGTH) == (size_t)-1) {

                perror("mbstowcs");
                exit(EXIT_FAILURE);
            }

            if (mbstowcs(s2buf, " orthis", S2LENGTH) == (size_t)-1) {

                perror("mbstowcs");
                exit(EXIT_FAILURE);
            }

            if (mbstowcs(test1, "abcmnexyz orthis", S1LENGTH + SIZE)

                perror("mbstowcs");
                exit(EXIT_FAILURE);
            }

  /* Concatenate s1buf with SIZE characters from s2buf, placing the */
  /* result into s1buf. Then compare s1buf with the expected result */
  /* in test1.                                                      */

            wcsncat(s1buf, s2buf, SIZE);

            for (i = 0; i <= S1LENGTH + SIZE - 2; i++) {
                /* Check that each character is correct */
                if (test1[i] != s1buf[i]) {
                    printf("Error in wcsncat\n");
                    exit(EXIT_FAILURE);
                }

            }

            printf("Concatenated string: <%S>\n", s1buf);
        }

      Running the example produces the following result:

        Concatenated string: <abcmnexyz or>