Scope CS Thinking Example 2

Follow the full solution, then compare it with the other examples linked below.

Example 2

hard
Explain why using global variables inside functions is generally discouraged.

Solution

  1. 1
    Step 1: Global variables can be changed by any part of the program, making it hard to track their value.
  2. 2
    Step 2: Functions that modify globals have side effects — their behaviour depends on external state, making testing and debugging harder.
  3. 3
    Step 3: Better practice: pass values as parameters and return results, keeping functions self-contained.

Answer

Global variables make programs harder to debug and maintain. Functions should use parameters and return values instead.
Minimising global state is a key principle of clean code. Functions that rely only on their parameters are predictable, testable, and reusable.

About Scope

The region of a program where a variable is accessible. Variables defined inside a function have local scope and exist only within that function. Variables defined outside all functions have global scope and are accessible from anywhere in the program.

Learn more about Scope →

More Scope Examples

Example 1 medium

What is the output? SET x = 10. FUNCTION addFive(): SET x = 5. RETURN x + 5. OUTPUT addFive(). OUTPU

Example 3 medium

What is the output? SET y = 100. FUNCTION test(): OUTPUT y. test(). Will this work, or will there be

Example 4 medium

What is the output? Explain any errors. SET count = 0 FUNCTION increment() SET count = count + 1

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