#!/usr/bin/perl -w
################################################################
#
# Corpus Analysis and Programming, Homework #3.
#
# Source: PerlHTP, Exercise 3.11.
#
# Programmed by William Yeh, 2002/09/26.
#
################################################################


#
# first, we declare several variables to hold the state...
#

$count = 0;    # number of numbers input so far
$sum   = 0;    # the sum of all integers so far
# $largest;    # later we'll use this variable to hold the largest one
# $smallest;   # later we'll use this variable to hold the smallest one


print "Please input a series of numbers...\n";

#
# now we enter the main loop of the whole program...
#

while ($data = <STDIN>) {
  chomp $data;

  next if length($data) < 1;  # skip this item if empty line
                        # the keyword "next" is to be explained in Chapter 5.


  ++$count;             # increment the counter
  $sum += $data;        # calculate the new sum

  if ($count == 1) {    # special case: this is the 1st input!
    $largest = $smallest = $data;
  }
  elsif ($data > $largest) {
    $largest  = $data;
  }
  elsif ($data < $smallest) {
    $smallest = $data;
  }

  # NOTE: Since the 3 conditions above are mutually exclusive,
  # we do not program in the following less efficient (but still correct) way:
  #
  #       if ($count == 1) {    # special case: this is the 1st input!
  #         $largest = $smallest = $data;
  #       }
  #       else {                # general case
  #         $largest  = $data  if ($data > $largest);
  #         $smallest = $data  if ($data < $smallest);
  #       }

}

if ($count < 1) {  # no input
  print "Sorry, no input at all.\n";
}
else {
  $average = $sum / $count;
  print "Total number of input: $count\n",
        "The largest: $largest\n",
        "The smallest: $smallest\n",
        "The average: $average\n";
}