Lesson 17 of 55
8 mins readPython Labeled Loops & Nested Control
In Plain English
Perl supports loop labels (conventionally in `UPPERCASE:`) allowing `last LABEL;` or `next LABEL;` to break or continue outer loops from deep inside nested loops.
Deep Dive: How It Works
Label Syntax: Place `LABEL:` immediately before `for`, `while`, or `until`.
Targeted Control: `last OUTER;` terminates the named outer loop, not just the inner one.
Matrix Search: Ideal for exiting multi-dimensional scans when a match is found.
Core Rules to Remember
Uppercase Convention: Labels are usually uppercase identifiers (e.g., `OUTER:`, `ROW:`).
Multi-Level Break: Allows exiting multiple nesting levels cleanly.
Live Interactive Example
Hit Run Code to see it liveBreaking Outer Loop on Match
Python 3.12
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Output Console
Click "Run Code" to view the rendered output.
How it works: last OUTER immediately terminated both inner and outer loops.
Your Turn: Micro Challenge
No pressure! Edit the starter code below and test your solution with instant feedback.
Micro Exercise
Break Nested Loop with Label
- Label an outer loop `ROW: for my $i (1..3)`.
- Inside an inner loop `for my $j (1..3)`, if `$i == 2`, call `last ROW;`.
- Otherwise print `"[$i,$j] "`.
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Sandbox Output
Click "Run & Check" to test your solution.
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