PHP
Arrays
An array is a data structure that stores one or
more similar type of values in a single value. For example if you want to store
100 numbers then instead of defining 100 variables its easy to define an array
of 100 length.
There are three different kind of arrays and each
array value is accessed using an ID c which is called array index.
·
Numeric
array − An array with a numeric
index. Values are stored and accessed in linear fashion.
·
Associative
array − An array with strings as
index. This stores element values in association with key values rather than in
a strict linear index order.
·
Multidimensional
array − An array containing one
or more arrays and values are accessed using multiple indices
NOTE −
Built-in array functions is given in function reference PHP Array
Functions
Numeric Array
These arrays can store numbers, strings and any
object but their index will be represented by numbers. By default array index
starts from zero.
Example
Following is the example showing how to create and
access numeric arrays.
Here we have used array() function
to create array. This function is explained in function reference.
<html>
<body>
<?php
/* First
method to create array. */
$numbers = array( 1, 2, 3, 4, 5);
foreach( $numbers as $value ) {
echo "Value
is $value <br />";
}
/*
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 <br />";
}
?>
</body>
</html>
This will produce the following result −
Associative
Arrays
The associative arrays are very similar to numeric
arrays in term of functionality but they are different in terms of their index.
Associative array will have their index as string so that you can establish a
strong association between key and values.
To store the salaries of employees in an array, a
numerically indexed array would not be the best choice. Instead, we could use
the employees names as the keys in our associative array, and the value would
be their respective salary.
NOTE −
Don't keep associative array inside double quote while printing otherwise it
would not return any value.
Example
<html>
<body>
<?php
/* First method to associate create array. */
$salaries = array("mohammad" => 2000, "qadir" => 1000, "zara" => 500);
echo "Salary
of mohammad is ".
$salaries['mohammad'] . "<br />";
echo "Salary
of qadir is ". $salaries['qadir']. "<br />";
echo "Salary
of zara is ". $salaries['zara']. "<br />";
/*
Second method to create array. */
$salaries['mohammad'] = "high";
$salaries['qadir'] = "medium";
$salaries['zara'] = "low";
echo "Salary
of mohammad is ".
$salaries['mohammad'] . "<br />";
echo "Salary
of qadir is ". $salaries['qadir']. "<br />";
echo "Salary
of zara is ". $salaries['zara']. "<br />";
?>
</body>
</html>
This will produce the following result −
Multidimensional
Arrays
A multi-dimensional array each element in the main
array can also be an array. And each element in the sub-array can be an array, and
so on. Values in the multi-dimensional array are accessed using multiple index.
Example
In this example we create a two dimensional array
to store marks of three students in three subjects −
This example is an associative array, you can
create numeric array in the same fashion.
<html>
<body>
<?php
$marks = array(
"mohammad" => array (
"physics" => 35,
"maths" => 30,
"chemistry" => 39
),
"qadir" => array (
"physics" => 30,
"maths" => 32,
"chemistry" => 29
),
"zara" => array (
"physics" => 31,
"maths" => 22,
"chemistry" => 39
)
);
/*
Accessing multi-dimensional array values */
echo "Marks
for mohammad in physics : " ;
echo $marks['mohammad']['physics'] . "<br />";
echo "Marks
for qadir in maths : ";
echo $marks['qadir']['maths'] . "<br
/>";
echo "Marks
for zara in chemistry : " ;
echo $marks['zara']['chemistry'] . "<br
/>";
?>
</body>
</html>
This will produce the following result −
Marks for mohammad in physics : 35
Marks for qadir in maths : 32
Marks for zara in chemistry : 39