CS 101 Notes 9/23/2010

Exam discussion:

Trace Code Questions:

A simple one:
   That is the result of 

    y = 5 + 2 * 3;

A harder one:

  What is the value of y in the println statement a in this code?

  int x = 0;
  int y = 0;

  while (x < 4)
   {
      y = y + 2;
      x = x + 1;
   }

  System.out.println (y);

   x: 0, 1, 2, 3, 4
   y: 0, 2, 4, 6, 8


Debugging:  What to do when the code doesn't work 

   We need to answer the question:
       "What is really going on?"

   ONe method to do this:  Debugging Print Statement


   int loopCounter = 1;
    
   while ( loopCounter < 10 )
     {
       System.out.println ("Debug 1: " + loopCounter);
       // do something

       loopCounter ++ ;
     }

Two types of errors:
   1. Syntax Errors  - Easier to fix (automatically 
                           detected)
   2. Logic Errors   - Harded to fix because they are 
                           harder to detect