? PHP Exception Handling – Throwing Exceptions

? Quick Overview

In PHP, exceptions provide a structured and maintainable way to handle runtime errors. Using the throw keyword, you can immediately interrupt normal execution and transfer control to a corresponding catch block.

? Key Concepts

• Exceptions represent abnormal or unexpected runtime conditions
• throw creates and triggers an exception object
• try-catch blocks handle exceptions safely
• Execution stops immediately when an exception is thrown

? Syntax & Theory

The throw statement creates an instance of the Exception class (or a subclass). PHP then looks for the nearest matching catch block. If none is found, the script terminates with a fatal error.

? Code Example

// Function that throws an exception for negative numbers
<?php
function checkNumber($number) {
    if ($number < 0) {
        throw new Exception("Negative numbers are not allowed: $number");
    }
    echo "Number is: $number<br>";
}

try {
    checkNumber(10);
    checkNumber(-5);
}
catch (Exception $e) {
    echo "Caught exception: " . $e->getMessage();
}
?>

? Live Output / Explanation

? Interactive Understanding

Imagine exceptions as emergency exits in your program. Once triggered, PHP jumps directly to the error-handling logic instead of continuing blindly. This keeps applications stable and predictable.

? Use Cases

• Validating user input
• Database connection failures
• File handling errors
• Business rule enforcement