Web Application Development using PHP Chapter 4

CN5109
WEB APPLICATION
DEVELOPMENT
Chapter 4
PHP Array

PHP Array
• An array is a special variable, which can hold more than one
value at a time.
• If you have a list of items (a list of car names, for example),
storing the cars in single variables could look like this:
$cars1 = "Volvo";
$cars2 = "BMW";
$cars3 = "Toyota";
• However, what if you want to loop through the cars and find a
specific one? And what if you had not 3 cars, but 300?
• An array can hold many values under a single name, and you
can access the values by referring to an index number.

PHP Array
• In PHP, the array() function is used to create an array:
• There are three types of arrays:
• Indexed arrays - Arrays with a numeric index
• Associative arrays - Arrays with named keys
• Multidimensional arrays - Arrays containing one or more arrays
Syntax:
array();

Indexed Arrays
• There are two ways to create indexed arrays
• The index can be assigned automatically (index always starts
at 0):
• The following example creates an indexed array named $cars,
assigns three elements to it, and then prints a text containing
the array values:
$cars[0] = "Volvo";
$cars[1] = "BMW";
$cars[2] = "Toyota";
<?php
$cars = array("Volvo", "BMW", "Toyota");
echo "I like " . $cars[0] . ", " . $cars[1] . " and " . $cars[2] . ".";
?>

Indexed Arrays
• The count() function is used to return the length (the number
of elements) of an array:
<?php
$x = count($cars);
Echo “The total is $x”;
?>

Indexed Arrays
• To loop through and print all the values of an indexed array,
you could use a for loop, like this:
<?php
$arrlength = count($cars);
for($x = 0; $x < $arrlength; $x++) {
echo $cars[$x];
echo " ";
}
?>

Associative Arrays
• Associative arrays are arrays that use named keys that you
assign to them.
• There are two ways to create an associative array:
or
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
$age['Peter'] = "35";
$age['Ben'] = "37";
$age['Joe'] = "43";

Associative Arrays
• The named keys can then be used in a script:
<?php
echo "Peter is " . $age['Peter'] . " years old.";
?>

Associative Arrays
• To loop through and print all the values of an associative array,
you could use a foreach loop, like this:
<?php
foreach($age as $x => $x_value) {
echo "Key=" . $x . ", Value=" . $x_value;
echo " ";
}
?>

Try This
<?php
// First method to create array.
$numbers = array( 1, 2, 3, 4, 5);
foreach( $numbers as $value )
{
echo "Value is $value ";
}
// Second method to create array.
$numbers[0] = "one";
$numbers[1] = "two";
$numbers[2] = "three";
$numbers[3] = "four";
$numbers[4] = "five";
foreach( $numbers as $value )
{
echo "Value is $value ";
}
?>

Try This
<?php
// First method to associate create array.
$salaries = array("mohammad" => 2000, "qadir" => 1000, "zara" => 500);
echo "Salary of mohammad is ". $salaries['mohammad'] . " ";
echo "Salary of qadir is ". $salaries['qadir']. " ";
echo "Salary of zara is ". $salaries['zara']. " ";
// Second method to create array.
$salaries['mohammad'] = "high";
$salaries['qadir'] = "medium";
$salaries['zara'] = "low";
echo "Salary of mohammad is ". $salaries['mohammad'] . " ";
echo "Salary of qadir is ". $salaries['qadir']. " ";
echo "Salary of zara is ". $salaries['zara']. " ";
?>

Sort Functions For Arrays
• The elements in an array can be sorted in alphabetical or
numerical order, descending or ascending.
• sort() - sort arrays in ascending order
• rsort() - sort arrays in descending order
• asort() - sort associative arrays in ascending order, according to
the value
• ksort() - sort associative arrays in ascending order, according to
the key
• arsort() - sort associative arrays in descending order, according to
the value
• krsort() - sort associative arrays in descending order, according to
the key

• Sort arrays in ascending order - alphabetical order
• Sort arrays in ascending order - numerical order
<?php
sort($cars);
?>
<?php
$numbers = array(4, 6, 2, 22, 11);
sort($numbers);
?>

• Sort arrays in descending order - alphabetical order
• Sort arrays in descending order - numerical order
<?php
rsort($cars);
?>
<?php
$numbers = array(4, 6, 2, 22, 11);
rsort($numbers);
?>

• Sort associative arrays in ascending order, according to the
value
• Sort associative arrays in ascending order, according to the
value
<?php
asort($age);
?>
<?php
arsort($age);
?>

• Sort associative arrays in ascending order, according to the key
• Sort associative arrays in descending order, according to the
key
<?php
ksort($age);
?>
<?php
krsort($age);
?>

Try This
<?php
$cars = array("Proton","Mazda","Toyota");
sort($cars); //sort array
$arrlength = count($cars);
for ($x=0;$x<$arrlength;$x++)
{
echo $cars[$x];
echo " ";
}
?>

Try This
<?php
$age = array("Zack"=>"40", "Bob"=>"37", "John"=>"43");
asort($age); //sort array
foreach($age as $value)
{
echo $value;
echo " ";
}
?>

Quiz
a. What are the arrays use for?
b. What are the three type of array?
c. List down any four examples of Array Sort Function.

Web Application Development using PHP Chapter 4

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Web Application Development using PHP Chapter 4