CS 111 - 9/18/12

Looping - Repeat the same sequence of operations
    multiple times.  Also called "iteration"


Types:  while, for, do while, "enhanced" for 

  For now, we will only use the while loops


Syntax:

      while ( <booleanExpression> )
         {
            <statements> ;
         }

   <booleanExpression> : evaluates to either TRUE or FALSE

   while the <booleanExpression> is TRUE we execute
     the <statements> in the BODY of the loop.

   The simplest <booleanExpressions> use 
         Relational Operators

   The Relational Operators include:

     ==    Equality
     !=    Inequality
     >     Greater Than
     >=    Greater Than or Equal
     <     Less Than
     <=    Less Than or Equal


    int var1;
    var1 = 0;


        var1 == 10  

---------------------------
   Print out the values from 0 to 10

   int count;
   count = 0;    /// initialization line

   while ( count <= 10 )
      {
        System.out.println (count);
        count = count + 1;           // increment Line
      }


 When dealing with loops beware of:

    1.  Infinite Loop
       -  We forgot the increment line
    2.  A loop that never executes
       -  We forgot the initialization line
    3.  A misplaced semicolon

        // ERROR !!!!!!!
        // Don't do this

        count = 0;    /// initialization line

        while ( count <= 10 ) ;  // ERROR with semicolon
           {
              System.out.println (count);
              count = count + 1;           // increment Line
           }


An example of a "Count down loop"
   int count;
   count = 10;    /// initialization line

   while ( count >= 1 )
      {
        System.out.println (count);
        count = count - 1;           // increment Line
      }


  Increment Operator   ++
  Decrement operator   --



     count = count + 1;

     count ++;
     ++ count;

   int count;
   count = 0;    /// initialization line

   while ( count < 10 )
      {
        System.out.println (count);
        count ++;           // increment Line
      }


    // BEWARE OF THE FOLLOWING
    count = 5;
    count = count++;
    System.out.println (count);

    count = 7;
    count = ++count;