Loop construct in Rust - Step-by-Step Execution

Concept Flow - Loop construct

Start

↓

Execute loop body

↓

Check condition or continue?

↓

Repeat loop body

No↓

Exit loop

The loop runs the body repeatedly until a break condition stops it.

Execution Sample

Rust

let mut count = 0;
loop {
    if count == 3 {
        break;
    }
    count += 1;
}

This Rust loop increases count from 0 until it reaches 3, then stops.

Execution Table

Step	count	Condition (count == 3)	Action	Loop continues?
1	0	false	count += 1 -> 1	Yes
2	1	false	count += 1 -> 2	Yes
3	2	false	count += 1 -> 3	Yes
4	3	true	break	No

💡 At step 4, count == 3 is true, so loop breaks and stops.

Variable Tracker

Variable	Start	After 1	After 2	After 3	Final
count	0	1	2	3	3

Key Moments - 2 Insights

Why does the loop stop when count reaches 3?

Because at step 4 in the execution_table, the condition count == 3 is true, triggering the break statement which exits the loop.

What happens if the break statement is missing?

The loop would run forever because there is no condition to stop it, as shown by the loop continuing 'Yes' in all steps except the break step.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of count at step 3?

A 2

B 3

C 1

D 0

💡 Hint

Check the 'count' column in the execution_table at step 3.

At which step does the loop stop running?

A Step 2

B Step 4

C Step 3

D Step 1

💡 Hint

Look at the 'Loop continues?' column to find when it says 'No'.

If the condition was changed to count == 5, when would the loop break?

A At step 3

B At step 4

C At step 6

D It would never break

💡 Hint

The loop breaks when count equals the condition; count increments by 1 each step.

Concept Snapshot

Rust loop construct syntax:
loop {
    // code
    if condition {
        break;
    }
}
The loop runs repeatedly until break is called.
Use break to stop the loop when a condition is met.

Full Transcript

This example shows a Rust loop that starts with count at 0. Each loop step checks if count equals 3. If not, it adds 1 to count and repeats. When count reaches 3, the break statement stops the loop. The execution_table tracks each step's count value, condition check, and whether the loop continues. The variable_tracker shows how count changes from 0 to 3. Key moments explain why the loop stops and what happens without break. The visual quiz tests understanding of count values and loop stopping points. This helps beginners see how Rust loops run step-by-step.