Gettype and typeof checks in PHP - Step-by-Step Execution

Concept Flow - Gettype and typeof checks

Start

↓

Variable defined

↓

Use gettype()

↓

Output type as string

↓

Use get_debug_type() (PHP 8.0+)

↓

Output type as string

↓

End

The program defines a variable, then uses gettype() and get_debug_type() to check and output its type as a string.

Execution Sample

PHP

<?php
$var = 123;
echo gettype($var) . "\n";
echo get_debug_type($var) . "\n";
?>

This code sets a variable to 123, then prints its type using gettype() and get_debug_type().

Execution Table

Step	Action	Variable	Function Called	Result	Output
1	Define variable	$var	N/A	123 (integer)	N/A
2	Call gettype()	$var	gettype($var)	"integer"	integer
3	Call get_debug_type()	$var	get_debug_type($var)	"int"	int
4	End	N/A	N/A	N/A	N/A

💡 All steps completed, variable type checked by both functions.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
$var	undefined	123 (int)	123 (int)	123 (int)	123 (int)

Key Moments - 2 Insights

Why does gettype() return "integer" but get_debug_type() returns "int"?

gettype() returns the full type name as a string like "integer", while get_debug_type() returns a shorter alias like "int". See execution_table steps 2 and 3.

Can get_debug_type() be used in all PHP versions?

No, get_debug_type() was introduced in PHP 8.0. gettype() works in all versions. This is why get_debug_type() is called after gettype() in the execution.

Visual Quiz - 3 Questions

Look at the execution table, what is the output of gettype($var) at step 2?

A "string"

B "int"

C "integer"

D "number"

💡 Hint

Check the 'Output' column in execution_table row for step 2.

At which step does the variable $var get defined?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Look at the 'Action' and 'Variable' columns in execution_table.

If $var was a string "hello", what would gettype($var) output?

A "int"

B "string"

C "integer"

D "bool"

💡 Hint

gettype() returns the type name as a string, see how it outputs "integer" for an int in execution_table step 2.

Concept Snapshot

PHP gettype() returns the type of a variable as a string like "integer".
PHP get_debug_type() (PHP 8.0+) returns a shorter type name like "int".
Use gettype() for compatibility with older PHP versions.
Both help check variable types during debugging or logic.
Example: gettype(123) -> "integer", get_debug_type(123) -> "int".

Full Transcript

This example shows how PHP checks variable types using gettype() and get_debug_type(). First, a variable $var is set to 123, an integer. Then gettype($var) is called, which returns the string "integer". Next, get_debug_type($var) is called, returning "int". The difference is that gettype() returns the full type name, while get_debug_type() returns a shorter alias. get_debug_type() requires PHP 8.0 or newer. This helps programmers understand what type a variable holds at runtime.

Practice

1. What does the PHP function gettype() return when called on a variable?

easy

A. A string describing the variable's type

B. An integer representing the type code

C. A boolean indicating if the variable is set

D. An object describing the variable

Solution

1. Step 1: Understand the purpose of gettype()

   The gettype() function returns the type of a variable as a string, such as "integer", "string", or "array".

2. Step 2: Compare options with gettype() behavior

   The option stating that it returns a string describing the variable's type is correct.

3. Final Answer:

   A string describing the variable's type -> Option A

4. Quick Check:

   gettype() = string description [OK]

Hint: Remember: gettype() always returns a string type name [OK]

Common Mistakes:

• Thinking gettype() returns a numeric code
• Confusing gettype() with isset()
• Assuming gettype() returns an object

2. Which of the following is the correct syntax to get the type of a variable $var using gettype() in PHP?

easy

A. gettype $var;

B. typeof $var;

C. typeof($var);

D. gettype($var);

Solution

1. Step 1: Recall correct function syntax in PHP

   PHP functions require parentheses around arguments, so gettype($var); is correct syntax.

2. Step 2: Check other options for syntax errors

   Syntax using typeof is invalid because it is not a PHP function. gettype $var; misses parentheses, which is invalid syntax.

3. Final Answer:

   gettype($var); -> Option D

4. Quick Check:

   Function call syntax = gettype($var) [OK]

Hint: Use parentheses with function calls in PHP [OK]

Common Mistakes:

• Using typeof instead of gettype()
• Omitting parentheses in function calls
• Confusing PHP syntax with JavaScript

3. What will be the output of the following PHP code?

$x = 3.14;
echo gettype($x);

medium

A. integer

B. double

C. float

D. string

Solution

1. Step 1: Identify the variable type

   The variable $x is assigned 3.14, which is a floating-point number.

2. Step 2: Understand gettype() output for floats

   In PHP, gettype() returns "double" for floating-point numbers, not "float".

3. Final Answer:

   double -> Option B

4. Quick Check:

   gettype(3.14) = double [OK]

Hint: Remember: PHP calls floats "double" in gettype() output [OK]

Common Mistakes:

• Expecting output to be "float" instead of "double"
• Confusing integer and float types
• Assuming gettype() returns "string" for numbers

4. Consider this PHP code snippet:

$value = true;
if (typeof($value) === 'boolean') {
    echo 'Boolean type';
} else {
    echo 'Not boolean';
}

What is the problem with this code?

medium

A. typeof is not a valid PHP function

B. Comparison operator === cannot be used with strings

C. Boolean values cannot be checked with typeof

D. The variable $value is not defined

Solution

1. Step 1: Check if typeof is a PHP function

   PHP does not have a built-in typeof() function; it uses gettype() instead.

2. Step 2: Analyze the impact of using typeof()

   Using typeof() causes a fatal error because the function does not exist.

3. Final Answer:

   typeof is not a valid PHP function -> Option A

4. Quick Check:

   typeof() invalid in PHP [OK]

Hint: Use gettype(), not typeof(), in PHP [OK]

Common Mistakes:

• Assuming typeof() exists in PHP like in JavaScript
• Thinking === cannot compare strings
• Ignoring variable initialization

5. In PHP 8.0+, the typeof operator returns a Type object instead of a string. Given this code:

$var = [1, 2, 3];
$type = typeof $var;
echo $type->name;

What will be the output?

hard

A. Type

B. object

C. error

D. array

Solution

1. Step 1: Verify typeof in PHP 8.0+

   PHP has no typeof operator or function in 8.0+ or any version; use gettype() instead.

2. Step 2: Predict code execution

   The undefined typeof causes a fatal error (e.g., "Call to undefined function"). No echo output.

3. Final Answer:

   error -> Option C

4. Quick Check:

   typeof invalid in PHP [OK]

Hint: PHP has no typeof; use gettype() [OK]

Common Mistakes:

• Believing typeof exists in PHP 8.0+
• Confusing PHP with JavaScript's typeof
• Expecting a Type object return