PHP variables are used to store values such as strings, numbers, or arrays. Once a variable is declared, it can be reused throughout your script. All variables in PHP begin with the $ symbol.

Variables are one of the core concepts in programming. To understand programming, you must have a clear understanding of what a variable is, how and where it is stored, and what happens to it during code execution. A variable is a value that can change during program execution.

In the previous lesson, we discussed that PHP supports variables. In this lesson, we'll take a look at one type of variable — string variables.

String variables in PHP are used to store values that consist of characters. A PHP string can be saved in a variable. Below is a PHP script that assigns the text "Hello, World!" to the string variable $txt:

<?php
$txt = "Hello, World!";
echo $txt;
?>

The result of the code above:

In the previous lesson, we explored string variables. Now, let’s take a look at numeric variables. The simplest type of number is the integer.

Integers in PHP

Integers are whole numbers in the range from –2,147,483,648 to 2,147,483,647. This range is determined by the 32-bit memory space used to store integers.

So far, we’ve learned that PHP supports numbers and strings. But this is not all—this lesson introduces another type of variable: Boolean variables. They are called Boolean because they are used to build logical structures in code.

We’ve already explored string and numeric variables, and learned that numeric variables in PHP can be of various types: integers, floats, booleans. Now it’s time to learn how to operate on them, modify them, and perform arithmetic.

Below are tables illustrating the use of different PHP operators.

I think we've reached the point where it's time... it's time to finally start programming. After this lesson, you can say you've written code in PHP. Quite often, you'll need to reuse pieces of code on different pages or in different PHP files. To avoid duplicating code, PHP provides functions.

Quite often, depending on circumstances, we have to make decisions. In programming—just like in life—actions depend on conditions. In life we use our head to make decisions, in PHP we use the if statement. For example: if it rains, I’ll take an umbrella; if it’s warm, we’ll go to the beach. In PHP, we evaluate expressions for truth and perform actions accordingly:

In the previous lesson, we learned about the if statement. The if statement allows us to check a condition and execute specific actions based on the result.

Now imagine you need to perform ten different checks and execute different actions based on each result. Sure, you could write this using multiple if statements:

In the previous lesson, we explored the use of functions in PHP. Now, we’ll dive deeper into how functions can be used. Previously, we used functions like this:

<?php
function myFunction() { // function declaration

}

$x = myFunction(); // function call
?>

But what happens if we call a function from within itself?

Up to this lesson, we’ve only been working with numeric and string variables. Now, let’s explore arrays in PHP. Arrays can contain both numeric and string variables, which is why they are called arrays.