Indexed array creation in PHP - Step-by-Step Execution

Concept Flow - Indexed array creation

Start

↓

Create empty array

↓

Add element at index 0

↓

Add element at index 1

↓

Add element at index 2

↓

Array ready with elements

↓

End

We start with an empty array and add elements one by one at increasing numeric indexes, creating an indexed array.

Execution Sample

PHP

<?php
$array = ["apple", "banana", "cherry"];
print_r($array);
?>

This code creates an indexed array with three fruits and prints it.

Execution Table

Step	Action	Array State	Index Assigned	Output
1	Create empty array	[]	N/A	No output
2	Add 'apple'	["apple"]	0	No output
3	Add 'banana'	["apple", "banana"]	1	No output
4	Add 'cherry'	["apple", "banana", "cherry"]	2	No output
5	Print array	["apple", "banana", "cherry"]	N/A	Array ( [0] => apple [1] => banana [2] => cherry )

💡 All elements added, array printed, execution ends.

Variable Tracker

Variable	Start	After 1	After 2	After 3	Final
$array	[]	["apple"]	["apple", "banana"]	["apple", "banana", "cherry"]	["apple", "banana", "cherry"]

Key Moments - 3 Insights

Why does the first element get index 0 automatically?

In PHP, indexed arrays start numbering from 0 by default, so the first added element is at index 0 as shown in step 2 of the execution table.

What if I add elements without specifying indexes?

PHP automatically assigns the next available numeric index, increasing by 1 each time, as seen in steps 2 to 4 where indexes 0, 1, and 2 are assigned.

Why does print_r show indexes even if I didn't write them?

print_r shows the internal array structure including indexes, which helps us see the numeric keys PHP assigned automatically (step 5).

Visual Quiz - 3 Questions

Look at the execution table, what is the array state after step 3?

A ["apple", "banana", "cherry"]

B []

C ["apple", "banana"]

D ["banana", "cherry"]

💡 Hint

Check the 'Array State' column at step 3 in the execution table.

At which step does the array get the element 'cherry'?

A Step 3

B Step 4

C Step 2

D Step 5

💡 Hint

Look for the action adding 'cherry' in the execution table.

If we added another element 'date' after 'cherry', what index would it get?

A 3

B 2

C 0

D 1

💡 Hint

Indexes start at 0 and increase by 1 for each new element, see variable_tracker for index progression.

Concept Snapshot

Indexed array creation in PHP:
$array = ["value1", "value2", "value3"];
Elements get numeric indexes starting at 0 automatically.
Use print_r($array) to see keys and values.
Adding elements without keys appends them with next index.

Full Transcript

This visual trace shows how PHP creates an indexed array by starting with an empty array and adding elements one by one. Each element gets a numeric index starting at 0 automatically. The execution table tracks each step: creating the array, adding 'apple' at index 0, 'banana' at index 1, and 'cherry' at index 2. Finally, print_r outputs the array showing the indexes and values. The variable tracker shows how the array grows after each addition. Common confusions include why indexes start at 0 and how PHP assigns indexes automatically. The quiz tests understanding of array state at different steps and index assignment rules.