Lesson 017
Functions & Procedures
Parameters · Return Values · Reuse
1:00How to bundle reusable steps into functions, pass inputs as arguments, get results back via return values, and keep variables isolated with local scope.
By the end, you can
- Explain what a function is and why it is preferable to copying code.
- Identify the four structural parts of a function definition.
- Trace the call/return flow: call → bind arguments → run body → return value.
- Distinguish parameters (definition placeholders) from arguments (values at the call).
- Explain what a return value is, and why lines after return never execute.
- Distinguish a function (returns a value) from a procedure (returns nothing).
- Describe local scope and predict what happens when a local variable is used outside its function.
- Apply the DRY principle and explain why functions support it.
- Diagnose the "no return" bug and the "missing argument" bug, and fix both.
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