Program Construction – GCSE Computer Science WJEC Revision

Basics of Program Construction

Program Construction: The process of writing a set of commands or instructions that a computer can interpret and execute.

Algorithms: A step-by-step set of operations to be performed. Algorithms are the building blocks of programs and define the logic of your code.
Flowcharts: A diagrammatic representation of an algorithm. Flowcharts can help visualise the flow of the program and make it easier to construct.
Pseudocodes: Not actual programming code but a representation of the code in English or in simple syntax. Useful for planning the program before actually coding.

Variables: These are named locations in memory to store values. A variable has a datatype i.e. integer, string, boolean, etc.
Constants: Similar to variables, they hold data, but their values remain unchanged throughout the program.
Operators: Symbols that perform specific operations like arithmetic, comparison, logical operations etc.
Control Flow Statements: These dictate the order in which instructions are executed. They include if statements, loops like for and while, and more complex constructs like switch statements.

Testing: A fundamental part of program construction to make sure the program works as expected. It involves trying various inputs and making sure the output is as expected.
Debugging: The process of finding and fixing errors (bugs) in your program. Debugging tools, or debuggers, can help track down the problem in your code.
Syntax Errors: These are errors in the code due to incorrect use of the programming language syntax. The program will not run until these are corrected.
Logical Errors: Errors that occur when the program compiles and runs but doesn’t produce the right output. Debugging and proper testing can help spot these errors.

Comments: Lines in your code meant for humans to read, not for the computer to execute. They are used to explain what the code does and why certain decisions were made.
Program Documentation: Information about the program which is useful for anyone trying to understand, use, or modify it. This includes the user manual, technical specification, and design documents.
Maintenance: The work done after the program is deployed. This includes fixing bugs, making enhancements, and ensuring the program is still functioning optimally over time.
Version Control Systems (VCS): Tools that help keep track of different versions of your code, allowing for collaboration and simplifying the process of integrating changes. Examples include Git and Mercurial.