Click here to download marathon.c.

/*********************************************
Get Time in Seconds

Times for marathon runners are kept the following
format: h:mm:ss.  So for example, my time might be
8:34:08.  Write a program that reads in a list of
one or more such times, separated by commas and
terminated by a semicolon, and prints out the
average time in seconds.  typical input might
look like:

   3:22:01, 2:58:27, 2:59:23, 3:05:00, 3:08:33;

And your program should print out 11200.8.
*********************************************/
#include <stdio.h>

int readtime();

/*********************************************
 ** main() function
 *********************************************/
int main() {
  // Initialization before loop
  printf("Enter lists of times in hh:mm:ss form,\n"
         "using , to separate and ; to terminate:\n");
  int totsecs = 0; // total sum of times read in (in seconds)
  int n = 0; // number of times read in
  char c;

  // Loop over each time entered by user
  do {
    totsecs += readtime();
    scanf("%c", &c); // reads in space or ;
    n++;
  } while(c != ';');

  // Write average time in seconds
  printf("Average in seconds: %g\n", totsecs / (double)n);

  return 0;
}

/*********************************************
 ** readtime() - this function reads a time
 ** in hh:mm:ss format from cin, and returns
 ** the time in seconds.
 *********************************************/
int readtime() {
  int h;
  int m;
  int s;
  scanf("%d:%d:%d", &h, &m, &s);
  return (h*60 + m)*60 + s;
}