Array key and value extraction in PHP - Step-by-Step Execution

Concept Flow - Array key and value extraction

Start with array

↓

Extract keys

→Store keys in new array

↓

Extract values

→Store values in new array

↓

Use keys and values separately

We start with an array, then extract its keys and values into separate arrays to use them individually.

Execution Sample

PHP

<?php
$array = ['a' => 1, 'b' => 2, 'c' => 3];
$keys = array_keys($array);
$values = array_values($array);
print_r($keys);
print_r($values);
?>

This code extracts keys and values from an associative array and prints them separately.

Execution Table

Step	Action	Array State	Result	Output
1	Define array	['a' => 1, 'b' => 2, 'c' => 3]	Array created
2	Extract keys	['a' => 1, 'b' => 2, 'c' => 3]	['a', 'b', 'c']
3	Extract values	['a' => 1, 'b' => 2, 'c' => 3]	[1, 2, 3]
4	Print keys	keys = ['a', 'b', 'c']	keys array	Array ( [0] => a [1] => b [2] => c )
5	Print values	values = [1, 2, 3]	values array	Array ( [0] => 1 [1] => 2 [2] => 3 )

💡 All keys and values extracted and printed.

Variable Tracker

Variable	Start	After Step 2	After Step 3	Final
$array	undefined	['a' => 1, 'b' => 2, 'c' => 3]	['a' => 1, 'b' => 2, 'c' => 3]	['a' => 1, 'b' => 2, 'c' => 3]
$keys	undefined	['a', 'b', 'c']	['a', 'b', 'c']	['a', 'b', 'c']
$values	undefined	undefined	[1, 2, 3]	[1, 2, 3]

Key Moments - 2 Insights

Why do keys become a simple list of strings instead of keeping their original association?

Because array_keys() returns only the keys as a plain indexed array, losing the original key-value association, as shown in step 2 of the execution_table.

Why do values become a zero-based indexed array instead of keeping their original keys?

Because array_values() returns only the values as a plain indexed array starting at 0, ignoring original keys, as seen in step 3 of the execution_table.

Visual Quiz - 3 Questions

Look at the execution_table at step 2, what is the content of $keys?

A ['a' => 1, 'b' => 2, 'c' => 3]

B ['1', '2', '3']

C ['a', 'b', 'c']

D [1, 2, 3]

💡 Hint

Check the 'Result' column at step 2 in execution_table.

At which step does $values get assigned its array?

A Step 3

B Step 2

C Step 1

D Step 4

💡 Hint

Look at variable_tracker for $values and see when it changes from undefined.

If the original array had numeric keys, how would array_keys() output look?

A An array of values

B An array of those numeric keys

C An associative array with keys and values swapped

D An empty array

💡 Hint

array_keys() always returns the keys as a simple indexed array, regardless of key type.

Concept Snapshot

PHP arrays have keys and values.
Use array_keys() to get all keys as a simple list.
Use array_values() to get all values as a simple list.
Both functions return indexed arrays starting at 0.
Useful to separate keys and values for processing.

Full Transcript

We start with an associative array with keys 'a', 'b', 'c' and values 1, 2, 3. Using array_keys(), we extract the keys into a new indexed array ['a', 'b', 'c']. Using array_values(), we extract the values into a new indexed array [1, 2, 3]. We print both arrays to see the separated keys and values. This helps when you want to work with keys and values separately in PHP.