Array push and pop in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add an element to the end of the array.

PHP

<?php
$fruits = ['apple', 'banana'];
array_[1]($fruits, 'orange');
print_r($fruits);
?>

Drag options to blanks, or click blank then click option'

Apop

Bshift

Cpush

Dunshift

Attempts:

3 left

💡 Hint

Common Mistakes

Using array_pop instead of array_push, which removes elements.

Using array_shift or array_unshift which work on the start of the array.

The array_push function adds one or more elements to the end of an array.

2fill in blank

medium

Complete the code to remove the last element from the array and store it in a variable.

PHP

<?php
$colors = ['red', 'green', 'blue'];
$lastColor = array_[1]($colors);
echo $lastColor;
?>

Drag options to blanks, or click blank then click option'

Ashift

Bpush

Cunshift

Dpop

Attempts:

3 left

💡 Hint

Common Mistakes

Using array_push which adds elements instead of removing.

Using array_shift which removes from the start.

The array_pop function removes the last element from an array and returns it.

3fill in blank

hard

Fix the error in the code to correctly add 'pear' to the fruits array.

PHP

<?php
$fruits = ['apple', 'banana'];
array_[1]($fruits, 'pear');
print_r($fruits);
?>

Drag options to blanks, or click blank then click option'

Apop

Bpush

Cshift

Dunshift

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping the order of arguments causes errors or unexpected behavior.

The array_push function requires the array as the first argument, then the element(s) to add.

4fill in blank

hard

Fill both blanks to add 'kiwi' and then remove the last element from the array.

PHP

<?php
$fruits = ['apple', 'banana'];
array_[1]($fruits, 'kiwi');
$removed = array_[2]($fruits);
echo $removed;
?>

Drag options to blanks, or click blank then click option'

Apush

Bpop

Cshift

Dunshift

Attempts:

3 left

💡 Hint

Common Mistakes

Using array_pop before array_push changes the array unexpectedly.

Using shift or unshift instead of push/pop.

First, array_push adds 'kiwi' to the end. Then, array_pop removes and returns the last element.

5fill in blank

hard

Fill all three blanks to add 'mango', remove the last element, and then add 'grape'.

PHP

<?php
$fruits = ['apple', 'banana'];
array_[1]($fruits, 'mango');
$removed = array_[2]($fruits);
array_[3]($fruits, 'grape');
print_r($fruits);
?>

Drag options to blanks, or click blank then click option'

Apush

Bpop

Cshift

Dunshift

Attempts:

3 left

💡 Hint

Common Mistakes

Using shift or unshift which affect the start of the array.

Mixing up the order of operations.

We add 'mango' with array_push, remove the last element with array_pop, then add 'grape' again with array_push.

Practice

1. What does the PHP function array_push do to an array?

easy

A. Adds one or more elements to the end of the array

B. Removes the first element from the array

C. Removes the last element from the array

D. Sorts the array in ascending order

Solution

1. Step 1: Understand the purpose of array_push

   array_push is used to add elements to the end of an existing array.

2. Step 2: Compare with other array functions

   Functions like array_pop remove elements, but array_push only adds elements at the end.

3. Final Answer:

   Adds one or more elements to the end of the array -> Option A

4. Quick Check:

   array_push = add elements at end [OK]

Hint: Remember: push means add at the end [OK]

Common Mistakes:

• Confusing array_push with array_pop
• Thinking array_push removes elements
• Assuming array_push sorts the array

2. Which of the following is the correct syntax to add an element 'apple' to the array $fruits using array_push?

easy

A. array_push('apple', $fruits);

B. array_push($fruits['apple']);

C. array_push($fruits => 'apple');

D. array_push($fruits, 'apple');

Solution

1. Step 1: Recall the function signature

   The correct syntax is array_push(array, value1, value2, ...), where the first argument is the array variable.

2. Step 2: Check each option

   array_push($fruits, 'apple'); correctly uses array_push($fruits, 'apple');. Others misuse argument order or syntax.

3. Final Answer:

   array_push($fruits, 'apple'); -> Option D

4. Quick Check:

   array_push(array, value) syntax [OK]

Hint: First argument is array, then values to add [OK]

Common Mistakes:

• Swapping argument order
• Using arrow => instead of comma
• Passing only one argument incorrectly

3. What will be the output of the following PHP code?

$colors = ['red', 'green'];
array_push($colors, 'blue');
$last = array_pop($colors);
print_r($colors);
echo $last;

medium

A. Array ( [0] => red [1] => green [2] => blue ) blue

B. Array ( [0] => red [1] => green ) blue

C. Array ( [0] => red [1] => green ) green

D. Array ( [0] => red [1] => green [2] => blue ) green

Solution

1. Step 1: Understand array_push effect

   array_push adds 'blue' to the end, so array becomes ['red', 'green', 'blue'].

2. Step 2: Understand array_pop effect

   array_pop removes and returns the last element 'blue', so array becomes ['red', 'green'] and $last = 'blue'.

3. Final Answer:

   Array ( [0] => red [1] => green ) blue -> Option B

4. Quick Check:

   push adds, pop removes last [OK]

Hint: Push adds last, pop removes last [OK]

Common Mistakes:

• Thinking pop removes first element
• Expecting array to still have 'blue'
• Confusing printed array and echoed value

4. Identify the error in the following PHP code snippet:

$numbers = [1, 2, 3];
array_pop($numbers, 2);
print_r($numbers);

medium

A. No error, code works fine

B. array_pop should be called before array initialization

C. array_pop accepts only one argument, extra argument causes error

D. array_pop cannot be used on numeric arrays

Solution

1. Step 1: Check array_pop function signature

   array_pop accepts only one argument: the array variable.

2. Step 2: Analyze the code

   Passing a second argument (2) is invalid and will cause an error.

3. Final Answer:

   array_pop accepts only one argument, extra argument causes error -> Option C

4. Quick Check:

   array_pop(array) only one argument [OK]

Hint: array_pop takes exactly one argument [OK]

Common Mistakes:

• Passing multiple arguments to array_pop
• Thinking array_pop removes multiple elements
• Assuming no error on extra arguments

5. Given an empty array $stack = [];, which sequence of PHP statements correctly adds 'first', 'second', then removes the last added element and stores it in $removed?

hard

A. array_push($stack, 'first'); array_push($stack, 'second'); $removed = array_pop($stack);

B. $removed = array_pop($stack); array_push($stack, 'first'); array_push($stack, 'second');

C. array_pop($stack, 'first'); array_pop($stack, 'second'); $removed = array_push($stack);

D. array_push('first', $stack); array_push('second', $stack); $removed = array_pop($stack);

Solution

1. Step 1: Add elements in correct order

   Use array_push($stack, 'first') and then array_push($stack, 'second') to add elements to the stack.

2. Step 2: Remove last element and store it

   Use $removed = array_pop($stack); to remove and save the last added element ('second').

3. Final Answer:

   array_push($stack, 'first'); array_push($stack, 'second'); $removed = array_pop($stack); -> Option A

4. Quick Check:

   Push adds, pop removes last [OK]

Hint: Push then pop to simulate stack behavior [OK]

Common Mistakes:

• Calling array_pop before pushing elements
• Passing arguments in wrong order
• Using array_pop with extra arguments