PHP Basics Tutorial – Variables in PHP

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Learn what variables are in PHP and how to use them. This beginner-friendly guide explains variable declaration, assignment, types, and case sensitivity with examples.

What are Variables?

Variables are used to store values such as strings, numbers, and arrays.
In PHP, variables are prefixed with a dollar sign ($).

Understanding PHP Variables:

A variable’s value can change while the program is running.
In PHP, you don’t have to declare a variable before giving it a value.
PHP automatically figures out the right data type based on the value you give.
Once you create a variable, you can use it again and again in your code.
The equals sign (=) is used to give a value to a variable.
Variable names are case-sensitive, so $name and $Name are different.

Declaring and Assigning Variables

Variables do not need to be declared before use in PHP. They are dynamically typed.

Example #1: Declaring Variables

<?php
$txt = "PHP is fun!";
echo $txt;  // Output: PHP is fun!
?>

Variable Types

PHP automatically converts a variable’s type based on the value assigned to it.

Example #2

<?php
$var = 10;  // Integer
$var = "Hello!";  // String
$var = 3.14;  // Float
?>

Example #3: variable example

<?php

$x = 5;
$y = 4;
echo $x + $y;

?>

Tasks

Task 1: Basic Variable Declaration and Output

Create a PHP script that declares a variable named $greeting and assigns it the value "Hello, PHP!".
Use echo to display the value of $greeting.
Run the script and verify the output.

Expected Output:

Hello, PHP!

Task 2: Changing Variable Values

Declare a variable $number and assign it the value 10.
Display the value of $number using echo.
Reassign $number to 20 and display it again.
Finally, reassign $number to "twenty" (a string) and display it.

Expected Output:

10
20
twenty

Task 3: Arithmetic with Variables

Declare two variables, $a and $b, and assign them the values 7 and 3, respectively.
Calculate and display the sum, difference, product, and quotient of $a and $b.
- Use echo to output each result with a label (e.g., “Sum: 10”).

Expected Output:

Sum: 10
Difference: 4
Product: 21
Quotient: 2.333...

Task 4: Dynamic Typing

Declare a variable $dynamic and assign it an integer value (e.g., 100).
Display the value and its type using echo and gettype() (e.g., echo gettype($dynamic);).
Reassign $dynamic to a string (e.g., "Dynamic PHP") and display its type again.
Reassign $dynamic to a float (e.g., 3.14) and display its type once more.

Expected Output:

100
integer
Dynamic PHP
string
3.14
double

Task 5: Combining Variables

Declare two variables: $firstName (assign your name) and $lastName (assign your surname).
Combine them into a third variable $fullName and display it.
- Hint: Use concatenation (. in PHP), e.g., $fullName = $firstName . " " . $lastName;.

Expected Output:

John Doe

References

[1] “PHP Variables,” Tutorial Republic. [Online]. Available: https://www.tutorialrepublic.com/php-tutorial/php-variables.php. [Accessed: Apr. 29, 2025].