How to Use var_dump in PHP: Syntax and Examples

Use var_dump() in PHP to display detailed information about a variable, including its type and value. Simply pass the variable as an argument to var_dump(), and it will print the information directly to the output.

Syntax

The var_dump() function takes one or more variables as arguments and outputs their type and value. It is useful for debugging to see exactly what a variable contains.

• var_dump(variable1, variable2, ...): Pass one or more variables separated by commas.
• Outputs type information (e.g., int, string, array) and the value.

php

var_dump(mixed $expression, mixed ...$expressions): void;

Example

This example shows how var_dump() displays the type and value of different variables including an integer, a string, and an array.

php

<?php
$number = 42;
$text = "Hello";
$array = [1, 2, 3];

var_dump($number);
var_dump($text);
var_dump($array);
?>

Output

int(42)
string(5) "Hello"
array(3) {
  [0]=>
  int(1)
  [1]=>
  int(2)
  [2]=>
  int(3)
}

Common Pitfalls

Some common mistakes when using var_dump() include:

• Forgetting it outputs directly and does not return a value.
• Using it in production code, which can expose sensitive data.
• Passing complex objects without understanding the verbose output.

Always use var_dump() for debugging only and remove it before deploying your code.

php

<?php
// Wrong: expecting var_dump to return a string
$output = var_dump(123);
echo $output; // outputs nothing useful

// Right: just call var_dump directly
var_dump(123);
?>

Output

int(123)

Quick Reference

Usage	Description
var_dump($var)	Displays type and value of $var
var_dump($var1, $var2)	Displays multiple variables at once
Use for debugging	Helps understand variable contents
Avoid in production	Can expose sensitive information

Key Takeaways

Use var_dump() to see detailed type and value information of variables.

var_dump() outputs directly and does not return a value.

Avoid leaving var_dump() calls in production code to protect data.

You can pass multiple variables to var_dump() separated by commas.

It is a simple but powerful tool for debugging PHP code.