Why error handling matters in PHP - Challenge Your Understanding

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this PHP code with error handling?

Look at this PHP code that tries to divide two numbers. What will it print?

PHP

<?php
function divide($a, $b) {
    try {
        if ($b == 0) {
            throw new Exception("Division by zero.");
        }
        return $a / $b;
    } catch (Exception $e) {
        return $e->getMessage();
    }
}

echo divide(10, 0);

A Fatal error: Division by zero

B Division by zero.

C 0

D 10

💡 Hint

Think about what happens when the divisor is zero and how the exception is handled.

The code throws an exception when dividing by zero. The catch block catches it and returns the error message, so the output is the string "Division by zero."

❓ Predict Output

intermediate

What happens if error handling is missing?

What will this PHP code output?

PHP

<?php
function divide($a, $b) {
    return $a / $b;
}

echo divide(10, 0);

A Fatal error: Division by zero

B Division by zero.

C 0

D 10

💡 Hint

What happens when you divide by zero in PHP without catching errors?

Without error handling, dividing by zero causes a fatal error and the script stops running.

🔧 Debug

advanced

Find the error in this PHP error handling code

There is a mistake in this PHP code that tries to handle errors. What is it?

PHP

<?php
function readFileContent($filename) {
    try {
        $content = file_get_contents($filename);
        if (!$content) {
            throw new Exception("File not found or empty.");
        }
        return $content;
    } catch (Exception $e) {
        return $e->getMessage();
    }
}

echo readFileContent("missing.txt");

A The Exception class is not imported.

B The try block is missing a catch block.

C The condition if (!$content) fails when file content is '0', causing false error.

D file_get_contents throws a fatal error, so try-catch won't work.

💡 Hint

Think about what happens if the file content is the string '0'.

The condition if (!$content) treats '0' as false, so it wrongly throws an exception even if the file exists and contains '0'.

🧠 Conceptual

advanced

Why is error handling important in PHP applications?

Choose the best reason why error handling is important in PHP applications.

A It prevents the application from crashing and allows graceful recovery.

B It makes the code run faster by skipping error checks.

C It hides all errors so users never see any messages.

D It automatically fixes bugs in the code.

💡 Hint

Think about what happens when something unexpected occurs in your program.

Error handling helps the program continue running or fail gracefully instead of crashing unexpectedly.

❓ Predict Output

expert

What is the output of this PHP code with nested try-catch?

Analyze this PHP code with nested try-catch blocks. What will it output?

PHP

<?php
function test() {
    try {
        try {
            throw new Exception("Inner error");
        } catch (Exception $e) {
            echo "Caught: " . $e->getMessage() . "\n";
            throw new Exception("Outer error");
        }
    } catch (Exception $e) {
        echo "Caught again: " . $e->getMessage() . "\n";
    }
}

test();

A Fatal error: Uncaught Exception: Outer error

B

Caught: Outer error
Caught again: Inner error

C

Caught: Inner error

D

Caught: Inner error
Caught again: Outer error

💡 Hint

Look carefully at how exceptions are re-thrown and caught in nested blocks.

The inner try throws "Inner error" which is caught and printed. Then it throws "Outer error" which is caught by the outer catch and printed.