🔄 PHP Type Casting – Convert Variables Safely and Clearly

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🧲 Introduction – Why Type Casting Matters in PHP

PHP is a loosely typed language, which means it automatically converts data types when needed. But sometimes, you want to control that conversion explicitly—especially when dealing with numbers, strings, booleans, or arrays. That’s where type casting comes in.

🎯 In this guide, you’ll learn:

• What type casting is in PHP
• How to cast between different data types
• Real-world examples of type conversion
• Best practices and pitfalls to avoid

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📘 What Is Type Casting in PHP?

Type casting means converting a variable from one data type to another. You can cast types manually using PHP’s casting syntax.

✅ PHP supports type casting for:

• Integer
• Float
• Boolean
• String
• Array
• Object
• NULL

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✍️ Type Casting Syntax in PHP

$converted = (target_type) $variable;

💡 Example:

$val = "100";
$intVal = (int) $val;

✅ Converts the string "100" into integer 100.

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🔢 Cast to Integer (int) or (integer)

<?php
$x = "25.75";
$intVal = (int) $x;
echo $intVal; // Outputs: 25
?>

✅ Only the whole number part is preserved.

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💧 Cast to Float (float) or (double) or (real)

<?php
$x = "42.5";
$floatVal = (float) $x;
echo $floatVal; // Outputs: 42.5
?>

✅ Works even if the original value was a string or integer.

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🔤 Cast to String (string)

<?php
$x = 123;
$strVal = (string) $x;
echo $strVal; // Outputs: "123"
?>

✅ Converts any data type into its string representation.

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✅ Cast to Boolean (bool) or (boolean)

<?php
$x = 0;
$boolVal = (bool) $x;
var_dump($boolVal); // bool(false)
?>

❌ Falsy Values That Become false:

• 0, "0", "", NULL, [], false

Everything else becomes true.

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📚 Cast to Array (array)

<?php
$x = "PHP";
$arrVal = (array) $x;
var_dump($arrVal);
?>

✅ Converts a scalar value into an array with index [0].

array(1) {
  [0] => string(3) "PHP"
}

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🧱 Cast to Object (object)

<?php
$x = ["lang" => "PHP"];
$objVal = (object) $x;
echo $objVal->lang; // Outputs: PHP
?>

✅ Arrays become objects with properties, integers become unnamed members.

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🚫 Cast to NULL – Not Supported

There is no way to directly cast to NULL using (null) in PHP.

But you can assign NULL:

$var = null;

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🧪 Real-World Example – Form Input Conversion

<?php
$input = $_POST["age"]; // Comes as a string
$age = (int) $input;

if ($age > 18) {
    echo "Eligible";
} else {
    echo "Not eligible";
}
?>

✅ Convert string to integer before comparison to ensure correct logic.

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🧰 Summary Table – Type Casting Examples

From → To	Syntax	Result Example
String → Int	(int) "42"	42 (integer)
Float → Int	(int) 99.99	99
String → Bool	(bool) "0"	false
Int → String	(string) 123	"123"
Array → Object	(object) [“a”=>1]	Object with property a = 1

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🛠️ Best Practices

Best Practice	Why It Matters
✅ Use explicit casting when needed	Avoids logic errors from type juggling
✅ Always cast user input	Ensures expected data type
❌ Don’t cast NULL to other types	May lead to unpredictable behavior
✅ Use var_dump() when debugging	Shows type + value

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📌 Summary – Recap & Next Steps

Type casting gives you control over PHP’s automatic type conversion, making your code safer and more predictable. It’s especially useful when handling input data, performing calculations, or formatting values.

🔍 Key Takeaways:

• Use (int), (float), (string), (bool), (array), (object) to cast types
• No direct cast to NULL — use $var = null instead
• Always cast user input before operations like math or comparison
• Avoid unintended type juggling by enforcing conversions explicitly

⚙️ Real-World Relevance:
Type casting is crucial in form handling, database operations, API responses, and anywhere strict data formats are required in PHP applications.

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❓ Frequently Asked Questions (FAQ)

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❓ What is type juggling in PHP?
✅ Type juggling is automatic type conversion by PHP during operations. Example: "5" + 1 becomes 6.

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❓ Can I cast a string to an object in PHP?
❌ No. Casting a string directly to an object doesn’t work. Convert it to an array first, then to an object.

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❓ Is there a (null) type cast in PHP?
❌ No. PHP does not support (null) casting. You must manually assign null using $var = null;.

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❓ What’s the difference between intval() and (int)?
✅ Both convert values to integer, but intval() is a function and can accept additional base parameters.

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❓ Should I cast form data types in PHP?
✅ Yes. Always cast $_POST or $_GET data to the expected type to avoid logic errors and security issues.

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