PHP - Arrays

Arrays are used to store multiple values in a single variable. In PHP, an array can hold multiple data types. In PHP, there are three types of arrays:

• Indexed arrays - Arrays with numeric index
• Associative arrays - Arrays with named keys
• Multidimensional arrays - Arrays containing one or more arrays

In this section we will discuss about indexed array. Other types of arrays are discussed in later sections.

Create an Indexed Array

An indexed array can be created using array() keyword. It can be initialized at the time of creation by specifying all elements of the array within the array() keyword and separated by comma (,) or it can also be initialized later by specifying value using index number.

Alternatively, [] can also be used instead of array().

Syntax

//creating an empty array
$MyArray = array();  
$MyArray = []; 

//creating an array with initialization
$MyArray = array(value1, value2, ...);
$MyArray = [value1, value2, ...]; 

//initialization after creation of array
$MyArray[index_number] = value;

Access element of an Indexed Array

An element of an indexed array can be accessed with it's index number. In PHP, the index number of an array starts with 0 as shown in the figure below:

The example below describes how to access elements of an array using its index number.

<?php
//creating an array with 3 elements
$MyArray = array('MON', 'TUE', 'WED');

//using index number to assign values
//to 4th and 5th elements of the array
$MyArray[3] = 'THU';
$MyArray[4] = 'FRI';

for ($i = 0; $i < count($MyArray); $i++) {
  //access element using index number
  echo "Value at position=$i is $MyArray[$i] \n";
}
?>

The output of the above code will be:

Value at position=0 is MON 
Value at position=1 is TUE 
Value at position=2 is WED 
Value at position=3 is THU 
Value at position=4 is FRI 

Modify elements of an Indexed Array

Any element of an indexed array can be changed using its index number and assigning a new value. Consider the example below:

<?php
//creating an array with 5 elements
$MyArray = array(10, 20, 30, 40, 50);

//changing the value of element at index=1
$MyArray[1] = 1000;

//displaying the array
print_r($MyArray);
?>

The output of the above code will be:

Array
(
    [0] => 10
    [1] => 1000
    [2] => 30
    [3] => 40
    [4] => 50
)

1-based Indexed Array

To create a 1-based indexed array the following example can be used:

<?php
$firstquarter = array(1 => 'JAN', 'FEB', 'MAR');
print_r($firstquarter);
?>

The output of the above code will be:

Array
(
    [1] => JAN
    [2] => FEB
    [3] => MAR
)

Loop over Array

By using for loop, while loop or foreach loop, each elements of an indexed array can be accessed.

For Loop over Array

In the example below, for loop is used to access all elements of the given array.

<?php
//creating an array with 5 elements
$MyArray = array(10, 20, 30, 40, 50);

for ($i = 0; $i < count($MyArray); $i++) {
  //access element using index number
  echo "\$MyArray[$i] = $MyArray[$i] \n";
}
?>

The output of the above code will be:

$MyArray[0] = 10 
$MyArray[1] = 20 
$MyArray[2] = 30 
$MyArray[3] = 40 
$MyArray[4] = 50 

While Loop over Array

Similarly, while loop is also be used to access elements of the array.

<?php
//creating an array with 5 elements
$MyArray = array(10, 20, 30, 40, 50);

$i = 0;
while($i < count($MyArray)) {
  //access element using index number
  echo "\$MyArray[$i] = $MyArray[$i] \n";
  $i++;
}
?>

The output of the above code will be:

$MyArray[0] = 10 
$MyArray[1] = 20 
$MyArray[2] = 30 
$MyArray[3] = 40 
$MyArray[4] = 50 

Foreach Loop over Array

In the example below, foreach loop is used to access all elements of an array.

<?php
//creating an array with 5 elements
$MyArray = array(10, 20, 30, 40, 50);

echo "MyArray contains: ";
foreach ($MyArray as $i) {
  echo $i." ";
}
?>

The output of the above code will be:

MyArray contains: 10 20 30 40 50

Complete PHP Array Reference

For a complete reference of all PHP Array functions, see the complete PHP Arrays Reference.