Lesson 10 of 59

5 mins read

Loop Control: break, continue & Labeled Jumps

In Plain English

`break` immediately terminates the innermost enclosing loop, while `continue` skips the remainder of the current iteration and proceeds to the next cycle. When working with deeply nested loops, Labeled Breaks (`break outerLoop;`) enable breaking out of multiple loop layers cleanly without artificial boolean flags.

The Mental Model

"`continue` is like skipping a track on a playlist to hear the next song; `break` is turning off the stereo entirely."

Deep Dive: How It Works

`break`: Exits the loop structure entirely.

`continue`: Bypasses remaining code in the loop body and advances the iterator/counter.

Loop Labels: Declared with an identifier followed by a colon (`outer: for (...)`), enabling targeted `break outer;` or `continue outer;`.

Syntax Blueprint

outerLoop: for (var r = 0; r < 5; r++) {
  for (var c = 0; c < 5; c++) {
    if (r == 2 && c == 2) break outerLoop; // Breaks BOTH loops
  }
}

Labeled loops allow breaking out of multiple nested loops simultaneously.

Core Rules to Remember

Early Termination: `break` prevents wasting CPU cycles scanning after a target match is found.

Skipping Cycles: `continue` cleans up loop bodies by bypassing invalid or empty records.

Labeled Jumps: Eliminates messy nested boolean flag variables.

Common Beginner Traps & How to Fix Them

Mistake:Using unlabeled `break` in a nested loop and expecting the outer loop to terminate.

Why it happens: Unlabeled `break` only exits the innermost loop.

How to fix: Apply a label to the outer loop (`outer: for (...)`) and execute `break outer;`.

Pro Tip: Combine `continue` with early validation checks to avoid wrapping the entire loop body inside a deep `if` block.

Live Interactive Example

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Filtering with continue and Labeled Matrix Break

Python 3.12

Output Console

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How it works: Skipped even numbers using continue and exited nested loops cleanly with a labeled break.

Your Turn: Micro Challenge

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Micro Exercise

Sum First Three Positive Numbers

Given list `final numbers = [-2, 5, -1, 10, 15, 20, 25];`.
Iterate through the list. If `n <= 0`, use `continue`.
Add `n` to `sum`, and `count++`. When `count == 3`, use `break`.
Print `Sum: $sum`.

Sandbox Output

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