Variable Examples in CS Thinking
Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Variable.
This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in CS Thinking.
Concept Recap
A named container in a program that stores a value, which can be read, updated, or replaced.
A labeled box you can put things in, take things out, or change what's inside.
Read the full concept explanation →How to Use These Examples
- Read the first worked example with the solution open so the structure is clear.
- Try the practice problems before revealing each solution.
- Use the related concepts and background knowledge badges if you feel stuck.
What to Focus On
Core idea: Variables give meaningful names to data values so programs can store, retrieve, and modify them.
Common stuck point: = means 'assign' not 'equals'. x = x + 1 is valid (not a paradox).
Worked Examples
Example 1
easyTrace: SET x = 7. SET y = x + 3. SET x = y * 2. OUTPUT x, y.
Solution
- 1 Step 1: x = 7.
- 2 Step 2: y = 7 + 3 = 10.
- 3 Step 3: x = 10 * 2 = 20. Output: x = 20, y = 10.
Answer
x = 20, y = 10.
Variables are named containers for storing values. When we reassign a variable, the old value is replaced. Other variables that used the old value are not affected.
Example 2
mediumShow how to swap the values of two variables a and b using a temporary variable. Trace with a = 5, b = 9.
Practice Problems
Try these problems on your own first, then open the solution to compare your method.
Example 1
easyWhat is the output? SET score = 0. SET score = score + 10. SET score = score + 5. OUTPUT score.
Example 2
mediumTrace this swap algorithm: SET A = 3. SET B = 8. SET temp = A. SET A = B. SET B = temp. What are A and B at the end, and why is temp needed?