Lesson 21 of 55
9 mins readStack & Queue Ops: push, pop, shift & unshift
In Plain English
Perl arrays provide built-in primitives for stack (LIFO) and queue (FIFO) data structures: `push`/`pop` at the end, and `unshift`/`shift` at the beginning.
Deep Dive: How It Works
push(@arr, $item): Appends item(s) to the end of the array.
pop(@arr): Removes and returns the last element.
unshift(@arr, $item): Prepends item(s) to the beginning of the array.
shift(@arr): Removes and returns the first element.
Core Rules to Remember
Stack (LIFO): Use `push` and `pop` for stack operations.
Queue (FIFO): Use `push` to enqueue and `shift` to dequeue.
Live Interactive Example
Hit Run Code to see it liveManipulating Array Boundaries
Python 3.12
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Output Console
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How it works: shift removed the front element; pop removed the rear element.
Your Turn: Micro Challenge
No pressure! Edit the starter code below and test your solution with instant feedback.
Micro Exercise
Push and Pop Stack Items
- Declare `my @stack = (10, 20);`
- Call `push(@stack, 30);` then `my $top = pop(@stack);`
- Print `"Popped: $top, Top is now: $stack[-1]\n"`.
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Sandbox Output
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