Archive:Debugging challenges

These debugging challenges are written in JavaScript, and designed to complement the units: ICAB4225A Automate processes and ICAT4221A Locate equipment, system and software faults

Challenge Set 1 - Lexical Errors

Lexical errors are introduced when the programmer enters symbols that are not part of the programming language. Unlike when you misspell a word in English, this inevitably leads to a breakdown in programming communications. See if you can see (or find) the lexical errors in the following code snippets...

<script type="text/javascript">
   var num1 = 2;
   var num2 = 3;
   var product = num1 x num2;
   alert("the product of " + num1 + " and " + num2 + " is " + product);
</script>

Challenge Set 2 - Syntactic Errors

A syntax error occurs when you use the right symbols, but in a way that doesn't make sense to the compiler or interpreter. Something like the English sentence: "You don't program good"

 <script type="text/javascript">
   var x;
   x=prompt("What is 5 x 5?");
   while (x != 25) do
   {
     alert("Wrong answer");
     x=prompt("What is 5 x 5?",0);
   }
   document.write("Right, the answer is " + x)
 </script>

Challenge Set 3 - Execution Errors

Execution errors are impossible requests made in perfectly correct programming terms.

 <script type="text/javascript">
   var weekdays=new Array("Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday")
   for (i=1; i<8; ++i)
   {
     document.write(weekdays[i] + "
");
   }    
 </script>

Challenge 4 - Logic Errors

These are errors introduced Through faulty design. Once again, the syntax is correct, but the results are unexpected

 <script type="text/javascript">
   document.write("counting from 1 to 10... ");
   for (i=1; i<11; i+=1)
   {
     document.write(++i + ' ');
   }    
 </script>