Exceptional handling and try catch in php with syntax and examples

Exception handling is a mechanism to handle runtime errors in a controlled manner. PHP provides try-catch blocks to handle exceptions.

Syntax:


try {
  // code that may throw an exception
} catch (ExceptionType $e) {
  // code to handle the exception
}


Example:


try {
  $x = 10 / 0;
} catch (DivisionByZeroError $e) {
  echo "Error: " . $e->getMessage();
}


Try-Catch Blocks:

- try: Contains code that may throw an exception
- catch: Catches and handles the exception
- finally: Optional block that executes regardless of an exception

Example:


try {
  $x = 10 / 0;
} catch (DivisionByZeroError $e) {
  echo "Error: " . $e->getMessage();
} finally {
  echo "Finally block executed";
}


Exception Types:

- Exception: Base exception class
- TypeError: Type-related exceptions
- DivisionByZeroError: Division by zero exceptions
- PDOException: PDO-related exceptions

Throwing Exceptions:

- throw: Throws an exception

Example:


function divide($a, $b) {
  if ($b == 0) {
    throw new DivisionByZeroError("Cannot divide by zero");
  }
  return $a / $b;
}

try {
  echo divide(10, 0);
} catch (DivisionByZeroError $e) {
  echo "Error: " . $e->getMessage();
}


Custom Exceptions:

- Create custom exception classes extending the Exception class

Example:


class CustomException extends Exception {
  public function __construct($message) {
    parent::__construct($message);
  }
}

try {
  throw new CustomException("Custom error message");
} catch (CustomException $e) {
  echo "Error: " . $e->getMessage();
}


Best Practices:

1. Use try-catch blocks for error handling
2. Catch specific exception types
3. Use finally blocks for cleanup code
4. Throw exceptions for errors
5. Create custom exceptions for application-specific errors
6. Test exception handling thoroughly

By understanding exception handling and try-catch in PHP, you can write robust and error-free code that handles runtime errors gracefully.