Data Types

Every value in PHP has a type . In this lesson you'll meet all eight, learn the four you'll use every single day, discover exactly which values count as falsy , and pick the right tool — get_debug_type , var_dump , is_* — to inspect any value.

Learn Data Types in our free PHP course — a beginner-friendly interactive lesson with worked examples, a practice exercise and a quick recall.

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 The Eight Types at a Glance

PHP sorts every value into one of eight types, grouped into three families. The four scalar types each hold a single value. The two compound types — array and object — hold collections. And two special types stand apart: null (no value at all) and resource (a live handle to a file, socket, or database). The cleanest way to ask PHP what something is, since PHP 8, is get_debug_type() .

Notice that get_debug_type() returns the real class name ( stdClass ) for objects — far more useful than the bare word object you'd get from gettype() .

2️⃣ The Four Scalar Types

Scalars are the atoms of PHP: string (text), int (whole numbers), float (decimals), and bool ( true / false ). The dividing line between int and float is the decimal point — and there's one classic surprise hiding in division.

The headline: / always returns a float, even when the result is a whole number. 10 / 2 is float(5) . If you need a true integer result, use intdiv(10, 2) instead.

3️⃣ Truthy & Falsy

Whenever a value sits in a boolean context — inside an if , a while , or a ternary — PHP converts it to true or false . There are exactly seven falsy values ; everything else is truthy. Learn this short list and a whole category of bugs disappears.

The two traps catch everyone once: the string "0" is falsy, but "0.0" and "false" are truthy — they're non-empty strings that aren't exactly "0" .

4️⃣ Compound Types: Arrays & Objects

When you need to hold many values together, you reach for a compound type. An array can be an ordered list or a key-value map — both report as array . An object bundles named properties; the built-in stdClass is a generic, empty object you can stick properties onto.

5️⃣ Inspecting Types

You'll constantly need to ask "what type is this?" Use get_debug_type() for an accurate name, the is_* family ( is_int , is_string , …) for yes/no checks, and is_numeric() to detect numbers stored inside strings.

Now you try. Fill each ___ so the printed type matches the comment, then run it.

🧩 Reorder Challenge

These lines are scrambled . They should build an array, count it, and print whether it's empty. Put them in the order that runs correctly.

You must create the array before you can count it, and you must compute $n and $isEmpty before echoing them. Reading a variable before it's assigned would trigger an "Undefined variable" warning, so every value has to be produced before it's used. Output: Count: 3 then has items .

🧠 Quick Recall

Predict the output before you reveal each answer.

Prints float(5) . The / operator always returns a float, even when the result is whole. Use intdiv(10, 2) for int(5) .

Prints bool(true) . Only the string "0" is falsy — "0.0" is a different, non-empty string, so it's truthy.

Prints array . Both lists and associative maps report as array — there's only one array type in PHP.

Common Errors (and the fix)

• An if ($price) never runs even though $price is "0" — the string "0" is falsy. Compare explicitly: if ($price !== "") or check with isset() .
• gettype() says "double" but you expected "float" — that's the legacy name. Use get_debug_type() for the modern, accurate float .
• Integer division gives a decimal — / always returns a float. Switch to intdiv($a, $b) when you want a whole number.
• is_numeric("42px") is unexpectedly false — that's correct: a string is only numeric if the whole thing parses as a number. Strip the unit first.

Pro Tips

• 💡 Default to get_debug_type() . It's the PHP 8 way and reports real class names for objects.
• 💡 Keep the falsy seven on a sticky note. false 0 0.0 "" "0" [] null — everything else is true.
• 💡 Reach for is_numeric() on user input before doing maths with it, since form data always arrives as strings.

📋 Quick Reference — Data Types

Type

Example

Notes

string

"hi"

Text, any length

int

42

Whole number

float

3.14

Decimal; gettype says "double"

bool

true

true / false

array

[1, 2]

List or map

object

new stdClass

Named properties

null

No value

resource

fopen(...)

External handle

Frequently Asked Questions

Mini-Challenge: Type Report

Write it yourself, run it on onecompiler.com/php or your own machine, then check against the expected output in the comments.

🎉 Lesson Complete!

• ✅ PHP has eight types: four scalar, two compound, two special
• ✅ string , int , float , bool are the everyday scalars
• ✅ / always yields a float — use intdiv() for whole division
• ✅ Exactly seven values are falsy; everything else is truthy
• ✅ get_debug_type() is the modern way to inspect a value
• ✅ Next lesson: Strings & String Functions — slice, search, and format text

Practice quiz

Continue this course

• Previous: Variables
• Next: Strings & String Functions