Variable CS Thinking Example 4
Follow the full solution, then compare it with the other examples linked below.
Example 4
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?
Solution
- 1 Step 1: temp stores the original value of A, so temp = 3. Then A is replaced with B, so A = 8.
- 2 Step 2: Finally B is set to temp, so B = 3. The temporary variable is needed so the original value of A is not lost during the swap.
Answer
A = 8 and B = 3. The variable temp temporarily stores A so the values can be swapped safely.
Variables hold values that can be updated during a program. Temporary variables are often used when data must be preserved while other assignments happen.
About Variable
A named container in a program that stores a value, which can be read, updated, or replaced. Variables have a name (identifier), a value (the data stored), and in many languages a type (what kind of data it holds).
Learn more about Variable →More Variable Examples
Example 1 easy
Trace: SET x = 7. SET y = x + 3. SET x = y * 2. OUTPUT x, y.
Example 2 mediumShow how to swap the values of two variables a and b using a temporary variable. Trace with a = 5, b
Example 3 easyWhat is the output? SET score = 0. SET score = score + 10. SET score = score + 5. OUTPUT score.