DAY 7
Arrays in PHP
·
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.
1. Numeric array − An array with a numeric
index. Values are stored and accessed in linear fashion.
2. 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.
3. Multidimensional array − An array containing one or
more arrays and values are accessed using multiple indices
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 −
Value is 1
Value is 2
Value is 3
Value is 4
Value is 5
Value is one
Value is two
Value is three
Value is four
Value is five
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 −
Salary of mohammad is 2000
Salary of qadir is 1000
Salary of zara is 500
Salary of mohammad is high
Salary of qadir is medium
Salary of zara is low
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
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