void main()
{
  // there are 3 types of loops, but they are all equivalent in power; some
  // forms are more natural for certain applications, which is why the 3 forms
  // exist; could get by with only the WHILE loop

/////////////////////////////////////////////////////
// while

  // the WHILE loop is just like the IF statement, except it's
  // an IF that gets done over and over again until the condition
  // is not true

  // a loop to print out numbers from 1 to 10

  int count=1;
  while (count<=10)
  {
    cout << count << endl;
    count=count+1;
  }


  // loop example from Animal House

  char answer='y';

  while ((answer=='Y')||(answer=='y'))
  {
    cout << "Thank you sir!  May I have another?\n";
    cin >> answer;
  }

/////////////////////////////////////////////////////
// do-while

  // for the last example, DO-WHILE is actually better; note the
  // inverted logic in the condition below, using ! for NOT

  do
  {
    cout << "Thank you sir!  May I have another?\n";
    cin >> answer;
  }
  while (!((answer=='Y')||(answer=='y')));

  // in a DO-WHILE, the loop is always executed at least once

/////////////////////////////////////////////////////
// for

  // the FOR loop is ideal when counting is involved, or when
  // a sequence is involved

  // add the numbers from 1 to 50

  int i, sum;

  sum=0;
  for (i=1; i<=50; ++i)
  {
    sum=sum+i;
  }


  // count down from 100

  for (i=100; i>0; --i)
  {
    cout << i << endl;
  }

  // as always, a single command counts as a block of code, so don't
  // need the curly braces when only one command in body; doesn't
  // hurt to have them though

  for (i=100; i>0; --i) cout << i << endl;   //count down from 100

  // the FOR loop can take less space than other loops, and can
  // make the intentions of the programmer clearer
  
}