Help with wait3() function

Hi.....I was wondering if anyone can help me with the following problem that I am having.  I just wrote a problem that forks a new child process and tracks the user and system time statistics for it.  I used the getrusage() function to track the statistics of the child process.  However, I used the wait() function to have the parent wait for the child to terminate.  I would like to rewrite my code to use the wait3() function instead of using the wait() function and print out the same results.  I have looked at the Unix man pages and some online resources but I can't seem to get it work correctly.  Below is a copy of my source code.  You will also find a commented out line that I tried to implement wait3() with but it did not seem to work.  Any help will be greatly appreciated.  Thanks :-)

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <sys/resource.h>
#include <sys/time.h>

int main(int argc, char *argv[])
{

        struct rusage ru_start;
        double sys;
        double user;
        pid_t pid;
        pid_t waitpid;
        time_t ltime;
        int status;


      time(&ltime);
      printf("Start Time: %s\n", ctime(&ltime));

      if ((pid = fork()) < 0)
      {
            perror("fork() failed");
            exit(1);
      }

      if (pid == 0)
      {
            printf("Child pid = %d, ppid = %d\n", getpid(), getppid());

            execl("child_program","child_program", NULL);
            perror("execl");
            exit(1);
      }

        /* waitpid = wait3(&status, WNOHANG, &ru_start); */

         waitpid = wait(NULL);  

        getrusage(RUSAGE_CHILDREN, &ru_start);    

        printf("user time is %ld.%06ld\n", ru_start.ru_utime.tv_sec, ru_start.ru_utime.tv_usec);
        printf("system time is %ld.%06ld\n", ru_start.ru_stime.tv_sec, ru_start.ru_stime.tv_usec);


        printf("got to the end\n");

}