Arrays in php

array();
three types of arrays:
• Indexed arrays - Arrays with numeric index
• Associative arrays - Arrays with named keys
• Multidimensional arrays - Arrays containing one
or more arrays

PHP Indexed Arrays
• two ways to create indexed arrays:
$cars=array("Volvo","BMW","Toyota");
Or :
• $cars[0]="Volvo";
$cars[1]="BMW";
$cars[2]="Toyota";

EXAMPLE
<?php
echo "I like " . $cars[0] . ", " . $cars[1] . " and " . $cars[2] .
".";
?>

Get The Length of an Array - The count() Function
used to return the length of an array:
<?php
echo count($cars);
?>

Loop Through an Indexed Array
<?php
$arrlength=count($cars);
for($x=0;$x<$arrlength;$x++)
{
echo $cars[$x];
echo "<br>";
}
?>

PHP Associative Arrays
• Associative arrays are arrays that use named keys that you
assign to them.
$age=array("Peter"=>"35","Ben"=>"37","Joe"=>"43");
or:
$age['Peter']="35";
$age['Ben']="37";
$age['Joe']="43";
• The named keys can then be used in a script:
Example
<?php
echo "Peter is " . $age['Peter'] . " years old.";
?>
•

Loop Through an Associative
Array
• use a foreach loop
Example
• <?php
foreach($age as $x=>$x_value)
{
echo "Key=" . $x . ", Value=" . $x_value;
echo "<br>";
}
?>

Multidimensional Arrays
• An array can also contain another array as a value, which in
turn can hold other arrays as well.
Example
<?php
// A two-dimensional array:
$cars = array
(
array("Volvo",100,96),
array("BMW",60,59),
array("Toyota",110,100)
);
?>

$families = array
(
"Griffin"=>array
(
"Peter",
"Lois",
"Megan"
),
"Quagmire"=>array
(
"Glenn"
),
"Brown"=>array
(
"Cleveland",
"Loretta",
"Junior"
)
);

Array
(
[Griffin] => Array
(
[0] => Peter
[1] => Lois
[2] => Megan
)
[Quagmire] => Array
(
[0] => Glenn
)
[Brown] => Array
(
[0] => Cleveland
[1] => Loretta
[2] => Junior
)
)

echo "Is " . $families['Griffin'][2] .
" a part of the Griffin family?";
• Output
• Is Megan a part of the Griffin family?

explode()
• Has 2 arguments the separator and source string
and returns an array.
echo $arr;
?>

implode()
• to reverse the process, joining the elements of an array into a
single string using user-supplied “glue.”
<?php
// define array
$arr = array('one', 'two', 'three', 'four');
// convert array to string
// output: 'one and two and three and four'
$str = implode(' and ', $arr);
echo $str;
?>

range()
• This function accepts two end points and returns an
array containing all the numbers between those end
points.
<?php
// define array
$arr = range(1,1000);
echo $arr;
?>

min() and max()
They accept an array of numbers and return the
smallest and largest values in the array respectively.
<?php
$arr = array(7, 36, 5, 48, 28, 90, 91, 3, 67, 42);
echo 'Minimum is ' . min($arr) . ' and maximum is ' .
max($arr);
?>

array_slice()
array_slice() function, which accepts three arguments: the original
array, the index position (offset) at which to start slicing, and
the number of elements to return from the starting offset.
<?php
$rainbow = array('violet', 'indigo', 'blue', 'green', 'yellow‘,'orange', 'red');
// output: ('blue', 'green', 'yellow')
$arr = array_slice($rainbow, 2, 3);
echo $arr;
?>
• To extract a segment from the end of an array (rather than the
beginning), pass array_slice() a negative offset
• $arr = array_slice($rainbow, -5, 3);

Adding and Removing Array Elements
• array_unshift() function adds an element to the
beginning of an array;
• array_shift() function removes the first element of
an array;
• array_push() function adds an element to the end of
an array;
• array_pop() function removes the last element of
an array.

<?php
$movies = array('The Lion King', 'Cars', 'A Bug's Life');
// remove element from beginning of array
array_shift($movies);
// remove element from end of array
array_pop($movies);
// add element to end of array
array_push($movies, 'Ratatouille');
// add element to beginning of array
array_unshift($movies, 'The Incredibles');
// print array
// output: ('The Incredibles', 'Cars', 'Ratatouille')
echo $movies;
?>

Removing Duplicate Array Elements
• array_unique() function, which accepts an array and
returns a new array containing only unique values.
<?php
$duplicates = array('a', 'b', 'a', 'c', 'e', 'd', 'e');
// output: ('a', 'b', 'c', 'e', 'd')
$uniques = array_unique($duplicates);
echo $uniques;
?>

Randomizing and Reversing
Arrays
• shuffle() function re-arranges the elements of an array
in random order,
• array_reverse() function reverses the order of an array’s
elements.
<?php
$rainbow = array('violet', 'indigo', 'blue', 'green', 'yellow‘,'orange', 'red');
// randomize array
shuffle($rainbow);
echo $rainbow;
// output: ('red', 'orange', 'yellow', 'green', 'blue‘, 'indigo', 'violet')
$arr = array_reverse($rainbow);
echo $arr;
?>

Searching Arrays
• in_array() function looks through an array for a
specified value and returns true if found.
<?php
// define array
$cities = array('London', 'Paris', 'Barcelona', 'Lisbon', 'Zurich');
// search array for value
echo in_array('Barcelona', $cities);
?>

• the array_key_exists() function looks for a match to
the specified search term among an array’s key
<?php
$cities = array("United Kingdom" => "London",
"United States" => "Washington",
"France" => "Paris“,"India" => "Delhi”);
// search array for key
echo array_key_exists('India', $cities);
?>

Sorting an array
• sort() function, which lets you sort numerically
indexed arrays alphabetically or numerically, from
lowest to highest value.
<?php
$data = array(15,81,14,74,2);
// output: (2,14,15,74,81)
sort($data);
echo $data;
?>

• asort() function, which maintains the correlation
between keys and values while sorting.
<?php
$profile = array("fname" => "Susan“,"lname" =>
"Doe“,"sex" => "female“,"sector" => "Asset
Management“ );
// output: ('sector' => 'Asset Management‘, 'lname' => 'Doe‘, 'fname' => 'Susan‘, 'sex' =>
'female')
asort($profile);
echo $profile;
?>

• ksort() function, which uses keys instead of
values when performing the sorting.
$profile = array("fname" => "Susan“,"lname" => "Doe",
"sex" => "female“,"sector" => "Asset Management”);
// output: ('fname' => 'Susan‘, 'lname' => 'Doe‘,'sector' => 'Asset Management‘, 'sex' =>
'female')
ksort($profile);
echo $profile;
?>
• To reverse the sorted sequence generated by sort(), asort(),
and ksort(), use the rsort(), arsort(), and krsort() functions
respectively.

Merging Arrays
• merge one array into another with its array_merge()
function, which accepts one or more array variables
<?php
$dark = array('black', 'brown', 'blue');
$light = array('white', 'silver', 'yellow');
// output: ('black', 'brown', 'blue‘, 'white', 'silver', 'yellow')
$colors = array_merge($dark, $light);
echo $colors;
?>

Comparing Arrays
• the array_intersect() function returns the values
common to two arrays
• array_diff() function returns the values from the first
array that don’t exist in the second.
<?php
$orange = array('red', 'yellow');
$green = array('yellow', 'blue');
// output: ('yellow')
$common = array_intersect($orange, $green);
echo $common;
// find elements in first array but not in second
// output: ('red')
$unique = array_diff($orange, $green);
echo $unique;
?>

PHP list() Function
• The list() function is used to assign values to a list of
variables in one operation.
• Syntax
list(var1, var2, ...)
• Example :
• <?php
$my_array = array("Dog","Cat","Horse");
list($a, , $c) = $my_array;
echo "Here I only use the $a and $c variables.";
?>

Arrays in php

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