8.1 · Lesson 7 of 7
Maintainable programs, procedures and functions
Syllabus 8.1.6Syllabus 8.1.7Syllabus 8.1.8
What this lesson covers
- Write procedures and functions with parameters
- Use local and global variables and library routines
- Write maintainable programs
Key vocabulary
- Maintainable program
- A program that is easy for others to read, understand and change.
- Meaningful identifier
- A name that describes what a variable, constant, array or subroutine stores or does.
- Comment
- A note in the code for humans, ignored by the translator. Starts with // in pseudocode and # in Python.
- Magic number
- A value typed straight into the code with no explanation. Use a constant instead.
- Subroutine
- A named block of code that does a specific task, and can be called from elsewhere in the program.
- Procedure
- A subroutine that carries out a task but doesn't return a value. Run with CALL.
- Function
- A subroutine that returns a value, so it can be used in an expression.
- Parameter
- A value passed into a subroutine, listed in brackets in its header.
- Argument
- The actual value given to a parameter when a subroutine is called.
- RETURN
- Sends a value back from a function to where it was called.
- Local variable
- Declared inside a subroutine; can only be used there, and only exists while it runs.
- Global variable
- Declared in the main program; can be used anywhere in the program.
Check your learning
- Quick check: 4 questions
- Key vocabulary test: 12 terms
- Activity 1: Meaningful identifiers · 6 questions
- Activity 2: Which comment? · 5 questions
- Activity 3: Procedure or function? · 6 questions
- Activity 4: Trace the subroutine · 6 questions
- Activity 5: Maintainable programs quiz · 8 questions