Exception

An exception is an event that occurs during the execution of a program that disrupts the normal flow of instructions. Exceptions are typically errors or unexpected conditions that a program must handle to avoid crashing or producing incorrect results.

Exceptions provide a way to signal and handle error conditions or other exceptional events in a controlled manner. When an exception occurs, the normal flow of execution is interrupted, and control is transferred to an exception handler, a block of code designed to respond to the specific error or condition.

Key Concepts of Exceptions:

1. Throwing an Exception: This is the act of signaling that an exceptional condition has occurred. In many programming languages, this is done using a throw or raise statement.
2. Catching an Exception: This involves intercepting the exception and providing a response. This is typically done using try and catch (or except) blocks.
3. Exception Handling: The process of responding to exceptions. This may involve logging the error, cleaning up resources, or attempting to recover from the error.
4. Exception Hierarchy: Many programming languages define a hierarchy of exception classes, allowing different types of exceptions to be caught and handled separately.
5. Unchecked and Checked Exceptions: In some languages (like Java), exceptions are categorized as checked (must be declared and handled) or unchecked (not required to be declared or handled).

Example: Consider an example of exception handling in JavaScript:

function divide(a, b) {
    if (b === 0) {
        throw new Error("Division by zero is not allowed");
    }
    return a / b;
}

try {
    let result = divide(10, 0);
    console.log(result);
} catch (error) {
    console.error("An error occurred: " + error.message);
}

Explanation of the Example:

• Throwing an Exception: The divide function checks if the denominator (b) is zero. If it is, the function throws an exception using throw new Error("Division by zero is not allowed").
• Catching an Exception: The try block contains the code that might throw an exception. If an exception is thrown, control is transferred to the catch block, where the error is handled by logging an error message.