FOR

  The for statement is used to loop continuously while a certain
  condition is true. The advantages over the while statement is that a
  count variable can be initialized and incremented quite easily. The
  for statement has the form:

       for (<expression1>; <expression2>; <expression3>)
         <statement>

  The first expression is the one that should initialize the count
  variable. For example, if you wanted to count from 1 to 100, and
  were keeping the count in a variable called 'num', the first ex-
  pression would be 'num = 1'. The second expression is the condi-
  tional test. As long as it evaluates to non-zero (TRUE), the state-
  ment will be executed. Following the above example, this expression
  would be 'num < 100'. The third expression is the one that is used
  to increment the count variable. For the above example, it would
  therefore be 'num = num + 1'. This for statement differs in format
  from that in most other languages, but doing it this way is actually
  gives the programmer a lot of power and flexibility. Note that any
  of the expressions can be left empty, in which case they evaluate to
  non-zero (TRUE). Some examples are:

       for (count = 0; count < 100; count = count + 1)
        {
         printn(count);
         prints("");
        }

       for (c = 1000; c > 0; c = c - 1)
         do_this(c);

  The following would execute an infinite loop:

       for (;;)
         prints("Hello!");

  Note that there is really no restriction on what the expressions
  are. For example, the following is quite legal:

       for (c = num = 0; c < 100 && stat != -1; c = c + 1)
         {
          stat = func(num);
          num = func2();
         }

  The statements would only be executed if c was smaller than 100 and
  stat didn't equal -1.