Variables

By the end of this lesson you'll store text, numbers, and true/false values in $variables , tell PHP's types apart with var_dump , and sidestep the == pitfalls that trip up almost every beginner.

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Part of the free Php course at LearnCodingFast — hands-on lessons with examples you run in your browser, plus practice exercises and a quick quiz.

What You'll Learn in This Lesson

1️⃣ Creating Variables

A variable is a named place to keep a value so you can use it later. In PHP a variable name always begins with a $ , followed by a letter or underscore, then letters, numbers, or underscores — for example $name or $first_name . You create one by assigning a value with a single = , which means "store this in the box" — not "is equal to". Names are case-sensitive , so $Name and $name are two different boxes.

Notice the last two lines: assigning to $age again simply replaces what was inside. A variable holds one value at a time — the most recent thing you put in it.

2️⃣ PHP's Data Types

The type of a value is what kind of thing it is. PHP has eight types in total — string (text), int (whole numbers), float (decimals), bool ( true / false ), null (no value), plus array , object , and callable for later lessons. You'll use the first five constantly. The single most useful tool for learning them is var_dump() , which prints both the type and the value.

Two things to file away: var_dump shows a string's length ( string(9) means 9 characters), and PHP confusingly calls a float a "double" when you ask gettype() . That's a historical quirk — double and float mean the same thing in PHP.

3️⃣ Dynamic, Loose Typing

Unlike Java or C#, PHP is dynamically typed : you never write the type when you create a variable, and PHP works it out from the value. The same variable can even change type later — put text in it now, a number in it next. This is called loose typing , and it's flexible and fast to write, but it's also the reason for the comparison surprises you'll meet in section 5.

4️⃣ Quotes, Interpolation & Concatenation

How you quote a string changes what PHP does with it. Double quotes ( "..." ) interpolate — PHP swaps any $variable inside for its value and processes escapes like \n . Single quotes ( '...' ) are literal — you get the characters exactly as typed, $name and all. To stick strings together, use the dot operator ( . ), which is PHP's concatenation operator (not + ).

Now you try. Fill in each ___ using the 👉 hint, then run it and check against the Output panel.

One more — this time about quoting and joining strings.

5️⃣ Type Juggling: == vs ===

Type juggling is PHP automatically converting types during an operation — "5" + 3 gives 8 because the string is turned into a number. It also happens during loose comparison with == , which converts both sides to a common type first. That's why 5 == "5" is true . The fix is strict comparison with === , which checks value and type, so 5 === "5" is false . Use === by default and only use == when you genuinely want juggling.

PHP 8 cleaned up the worst of the old traps (for example 0 == "hello" used to be true and is now false ), but loose comparison can still surprise you with empty values and null . Reaching for === removes the guesswork entirely.

6️⃣ Constants

A constant is a value that's fixed once and can never change — perfect for things like a tax rate or a maximum limit. Constants have no $ and are written UPPER_CASE by convention. Define one with const (the modern, preferred way) or the older define() function. Trying to reassign a constant is a fatal error — which is exactly the safety you want for values that must never drift.

7️⃣ Heredoc & Nowdoc

For multi-line text — an email body, a block of HTML — quotes get awkward. Heredoc ( LABEL ) is like double quotes spread over many lines: it interpolates your variables. Nowdoc ( 'LABEL' , with the label in single quotes) is like single quotes: everything is literal . In both, the closing label must sit at the start of its own line.

📋 Quick Reference — Variables & Types

No code is filled in this time — just a brief and an outline. Write it yourself, run it on onecompiler.com/php or your own machine, then check your result against the expected output in the comments. This is exactly the write-run-check loop you'll use on every real script.

Practice quiz

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