While Loop CS Thinking Example 3

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

Example 3

medium
Trace: SET total = 0. SET i = 1. WHILE i <= 4: total = total + i. i = i + 1. OUTPUT total.

Solution

  1. 1
    Step 1: i=1: total=0+1=1, i=2. i=2: total=1+2=3, i=3. i=3: total=3+3=6, i=4. i=4: total=6+4=10, i=5.
  2. 2
    Step 2: i=5: 5 <= 4 is false, loop ends. Output: 10.

Answer

1010. Sum of 1+2+3+4.
This WHILE loop implements the accumulator pattern to sum consecutive integers. The loop variable i controls both the value added and when the loop terminates.

About While Loop

A control structure that repeats a block of code as long as a specified condition remains true. The condition is checked before each iteration, and if it is false from the start, the loop body never executes at all.

Learn more about While Loop →

More While Loop Examples

Example 1 medium

Trace: SET n = 1. WHILE n < 100: n = n * 2. OUTPUT n. How many iterations?

Example 2 medium

Write a WHILE loop that asks the user for input until they type 'quit'.

Example 4 medium

Trace this code and state the final output: SET n = 1 SET result = 1 WHILE n < 5 SET n = n + 1

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Related Concepts

IterationFor Loop