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 50 numbers then instead of defining 50 variables its easy to define an array of 50 length.
There are three different kind of arrays and each array value is accessed using an ID c which is called array index.
- Indexed arrays − 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
Indexed 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.
<?php /* 1stmethod to create array. */ $numbers = array( 1, 2, 3, 4, 5); foreach( $numbers as $value ) { echo "Value is $value <br />"; } /* 2nd 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 />"; } ?>
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: Associative arrays are arrays that use named keys that you assign to them.
There are two ways to create an associative array
<?php /* 1st method to associate create array. */ $salaries = array("rashed" => 200, "rasu" => 100, "rashidul" => 500); echo "Salary of rashed is ". $salaries['rashed'] . "<br />"; echo "Salary of rasu is ". $salaries['rasu']. "<br />"; echo "Salary of rashidul is ". $salaries['rashidul']. "<br />"; /* 2nd method to create array. */ $salaries['rashed'] = "high"; $salaries['rasu'] = "medium"; $salaries['rashidul'] = "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 />"; ?>
This will produce the following result −
Salary of rashed is 200 Salary of rasu is 100 Salary of rashidul is 500 Salary of rashed is high Salary of rasu is medium Salary of rashidul 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.
<?php $marks = array( "rashed" => array ( "physics" => 35, "maths" => 30, "chemistry" => 39 ), "rasu" => array ( "physics" => 30, "maths" => 32, "chemistry" => 29 ), "rashidul" => array ( "physics" => 31, "maths" => 22, "chemistry" => 39 ) ); /* Accessing multi-dimensional array values */ echo "Marks for rashed in physics : " ; echo $marks['rashed']['physics'] . "<br />"; echo "Marks for rasu in maths : "; echo $marks['rasu']['maths'] . "<br />"; echo "Marks for rashidul in chemistry : " ; echo $marks['rashidul']['chemistry'] . "<br />"; ?>
This will produce the following result −
Marks for rashed in physics : 35 Marks for rasu in maths : 32 Marks for rashidul in chemistry : 39
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