3.2 Program development

• The stages of the program development cycle
• What an algorithm is, and its characteristics
• Pseudocode: keywords and structure
• Flowcharts: standard symbols
• Designing an algorithm for a real problem
• The three control structures: sequence, selection, iteration

• describe the stages of program development in computer programming
• write pseudocode to illustrate the logical flow of an algorithm
• represent the logical flow of an algorithm using a flowchart
• design an algorithm to solve a real-life problem
• appreciate the importance of using algorithms in problem solving

“What is the essence of the program development cycle?”

“Why are algorithms designed?”

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1. The program development cycle and algorithms
   40 min · 1 practice tasks · quiz
   The seven stages of building software, why design comes before coding, and what makes a set of steps a proper algorithm.
2. Pseudocode and flowcharts
   40 min · 1 practice tasks · quiz
   The two standard ways to write down an algorithm - pseudocode and flowcharts - the three control structures, and designing a solution to a real problem.
3. The essence of the program development cycle
   40 min · 1 practice tasks · quiz
   It is a loop, not a line. Errors are cheapest on paper. That is why design comes before typing.
4. Problem definition: what must it do?
   40 min · 1 practice tasks · quiz
   Name inputs, outputs, processing and constraints before any algorithm. A school-fee balance.
5. Program design: how will it work?
   40 min · 1 practice tasks · quiz
   Turn a definition into an algorithm on paper: pseudocode or a flowchart, still no language.
6. Coding: spelling the design in a language
   40 min · 1 practice tasks · quiz
   Coding translates a finished design into source code. If design was good, typing is mostly mechanical.
7. Testing and debugging
   40 min · 1 practice tasks · quiz
   Test with normal, extreme and invalid data. Debugging is fixing what testing found.
8. Implementation: putting it into real use
   40 min · 1 practice tasks · quiz
   Install, move real data, train the people who will click. A working file in the lab is not yet in use.
9. Maintenance: most of the life of a program
   40 min · 1 practice tasks · quiz
   Corrective, adaptive and perfective maintenance. This is why the cycle loops, and why it costs most.
10. Documentation: user and technical
    40 min · 1 practice tasks · quiz
    Two audiences. Written beside every stage, not after. Comments are technical docs inside the code.
11. Characteristics of a good algorithm
    40 min · 1 practice tasks · quiz
    Input, output, finiteness, definiteness, effectiveness - and generality as a sixth.
12. Sequence, selection and iteration
    40 min · 1 practice tasks · quiz
    Every algorithm is built from three structures. Languages change; these three do not.
13. Dry runs and trace tables
    40 min · 1 practice tasks · quiz
    Trace every variable after every step on paper. That is how design errors are caught cheaply.
14. Designing an algorithm for a real problem
    40 min · 1 practice tasks · quiz
    A matatu-fare or kiosk-change problem: definition, pseudocode, flowchart, dry run - the outcome.
15. From kiosk problem to maintained code
    40 min · 1 practice tasks · quiz
    Walk one Kenyan problem through all seven stages. Responsibility and unity are part of the method.