What is type juggling / type casting in PHP? PHP में type juggling / type casting क्या है?

Short Answer

By default, PHP passes variables to functions by value, meaning the function receives a copy of the variable; changing it inside the function does not affect the original. Passing by reference (using the & symbol) passes the actual memory address, so changing the variable inside the function alters the original variable.

Detailed Explanation & Code Example

1. Pass by Value (Default behavior)

function addTen($number) {
    $number += 10;
}

$myAge = 25;
addTen($myAge);
echo $myAge; 
// Output: 25. (The original variable is untouched)

2. Pass by Reference

Notice the & symbol before the parameter in the function signature.

function addTenByRef(&$number) {
    $number += 10;
}

$myAge = 25;
addTenByRef($myAge);
echo $myAge; 
// Output: 35. (The original variable was modified directly)

Interview Tip

Always note that PHP objects are passed by reference-like behavior by default. If you pass an object into a function and modify its properties, the original object outside the function will reflect those changes without needing the & symbol.