Simple Program Traces

These pages are intended to assist students trying to understand how various programming structures work in Turbo Pascal. They have been developed as dynamic pages using the PHP language.

Three pictures are provided for each stage as a program fragment is executed: the source code, the variables in RAM, and the screen.

The program line about to be executed is printed on an aquamarine background. Click on the "NEXT" link to trace through the code. You can also reverse the process by clicking on "PREV" in most situations.

Changes in RAM and new information on the screen are signaled by being printed in red. In some instances, you will be permitted to input data.

Further information about the exemplified programming concepts is available through the associated links to static web pages. This information includes flowcharts, pseudocode, and discussion. In the following list, the first link is to a static page, while the others are links to program traces.

1. From Problem to Program
   • A Complete Program -- write() vs. writeln()
     
   • A Complete Program -- writeln() only
     
2. Single- and Double-Option if Statements
   • Single-Option if Statement
     
   • Double-Option if Statement
     
3. Two Loops & Flow Charting
   • repeat-until Loop
     
   • while-do Loop
     
4. The Simplest For Loop
   • for-to-do Loop
     
   • for-downto-do Loop
     
5. Getting Good Data with the Repeat-Until Loop I
   • User-Friendly repeat-until Loop
     
6. Procedures II -- Passing Values & Addresses
   • Calling a Procedure with Variable Parameters
     
7. Sorting
   • Using an Insertion Sort on [20 31 17 47 34]
     
   • Using a Selection Sort on [20 47 31 17 34]
     
   • Using a Selection Sort II on [20 31 17 47 34]
     
   • Using a Bubble Sort on [20 17 47 31 34]
     
   • Using a Bubble Sort II on [20 31 17 47 34]