PHP Introduction Lecture #11

PHP ARRAYS

Hello All... welcome every one. I'm going to start PHP lectures for Very Beginners, who wants to learn PHP from very beginning. No matter if you do not have any basic programming concept. If you follow my tutorials I hope you will surely get some how good knowledge of PHP.

Today our Topic is

ARRAY

Array is special type of variable that stores similar or even multiple type of data either number, characters, of alphanumeric characters within a single array. A simple variable can store just a single value but an array can store multiple values, as an ordered collection of key-value pairs. There are two types of an array.

ð INDEXED AND ASSOCIATIVE ARRAY

·        Indexed arrays are used when you identify things or values by their position/indexes.

·        Key of indexed array are integer starts from 0. The index of an array always starts from 0.

·        Associative array string as keys and behaves like two column table.

·        Sometimes number is not appropriate for identifying any array value for that we assign names to them, that’s what we need an associative array.

ð Declaring an Array

i-                   Indexed Array

There are two ways by which an array can be declared.

$names = array(“John”, “Celina”, “Rock”, “Catherine”);

It’s important to write array keyword as it shows that the declared variable is array type variable. Each of above value is automatically assigned a key to that values “John”, “Celina”, “Rock”, “Catherine” starts from 0,1,2,3 respectively

Another way is assigning the key manually.

$names[0] = “John”;

$names[1] = “Celina”;

$names[2] = “Rock”;

$names[3] = “Catherine”;

Both of the ways are workable and second example is more clear I think, that at the 0 index of an array there is value that is “John” and at the 1^st index of an array there is value that is “Celina” and so on respectively. Let’s do the example

<?php

            $names[0] = “John”;

            $names[1] = “Celina”;

            $names[2] = “Rock”;

            $names[3] = “Catherine”;

            echo $names[0] . “ and “ . $names[2] . “ are brothers to each other”;

?>

And the result will be like this:

John and Rock are brothers to each other.

ii-                Associative Array

Just like Indexed an Associative array can be declared in two ways same as an indexed array, the difference is in indexed array key of any value is integer but in associative array key of value will be string. To create an associative array use `=>` symbol to separate indexes from values. Example

$student = array(“First_Name”=> ”John”, “Last_Name”=> “Smith”, “Age”=>”22”);

Here key is a string not a number and value is integer as well string. Look for another example of declaring an associative array.

$student[“First_Name”] = “John”;

$student[“Last_Name”] = “Smith”;

$student[“Age”] = “22”;

Just very simple and easy. Now print out some result.

<?php

echo  "Age of " . $student["First_Name"] . " is " . $student["Age"];

?>

This will result as: Age of John is 22.

If you want to see the structure and values of an array you can use two of the common functions print_r(array_variable) and var_dump(array_name), however print_r() gives less information as compared to var_dump(). So it is preferred to use var_dump() you can use and see the information about an array.

var_dump($student) or var_dump($names) or any of the array you have declared.

Hope that from above example it’s clear that an array can store multiple type of values and also you can print anything according to your need when needed. But remember you cannot initialize same key of indexed or associative array. Key should always be unique.

Thanks Guys. Any thing missing or any question from this topic you can comment below, I will be trying to solve and answer your question.

Our Next topic will be `Database`.

Good Luck J