PHP Basics Tutorial – Variables in PHP

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

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

Expected Output:

Hello, PHP!

Task 2: Changing Variable Values

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

Expected Output:

10
20
twenty

Task 3: Arithmetic with Variables

1. Declare two variables, $a and $b, and assign them the values 7 and 3, respectively.
2. 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

1. Declare a variable $dynamic and assign it an integer value (e.g., 100).
2. Display the value and its type using echo and gettype() (e.g., echo gettype($dynamic);).
3. Reassign $dynamic to a string (e.g., "Dynamic PHP") and display its type again.
4. 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

1. Declare two variables: $firstName (assign your name) and $lastName (assign your surname).
2. 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].