Exception Handling in Programming

Exception handling is a critical aspect of programming, enabling developers to manage unexpected or erroneous situations gracefully. In this article, we’ll discuss the concept of exception handling, its importance, and best practices for implementing it effectively in various programming languages.

What is Exception Handling?

Exception handling is a programming concept used to manage errors that occur during the execution of a program. When an error occurs, the normal flow of the program is disrupted. The program creates an “exception” object that contains information about the error. The process of responding to this exception is called “exception handling”.

Basics of Exception Handling :

Exception Handling mainly Revolves around two concepts one is Exception other is Handling.

• Exception: An exception is an unwanted event that interrupts the normal flow of the program.
• Handling: A block of Code that Handles or continues the flow of the program even after the exception is occurred (e.g. Try-Catch Block).

Components of Exception Handling:

Exception handling typically involves three main components:

1. Try Block: The code that may potentially throw an exception is enclosed within a try block. If an exception occurs within this block, the control is transferred to the corresponding catch block.
2. Catch Block: This block catches and handles the exceptions thrown within the try block. Each catch block is associated with a specific type of exception, allowing developers to handle different types of errors separately.
3. Finally Block (Optional): The finally block is executed regardless of whether an exception occurs or not. It is commonly used to perform cleanup tasks, such as closing files or releasing resources.

Exception Handling in C:

errno is a global variable indicating the error occurred during any function call and it is defined inside <errno.h> header file.

When a function is called in C, a variable named errno is automatically assigned a code (value) which can be used to identify the type of error that has been encountered. Different codes (values) for errno mean different types of errors.

C

// C program to check and rectify 
// divide by zero condition 
#include <stdio.h> 
#include <stdlib.h> 

void function(int); 

int main() 
{ 
    int x = 0; 
    function(x); 
    return 0; 
} 

void function(int x) 
{ 
    float fx; 

    if (x == 0) { 
        printf("Error: Division by Zero Error\n"); 
        exit(EXIT_FAILURE); 
    } 
    else { 
        fx = 10 / x; 
        printf("f(x) is: %.5f", fx); 
    } 
}

Output

Error: Division by Zero Error

Exception Handling in C++:

• try: This is used to specify a section of the code where a problem might occur and we want to handle it.
• catch: This is used to handle the problem that was thrown.
• throw: This is used when a problem occurs in the program.

C++

#include <iostream>
using namespace std;

// function to throw division by zero exception
void divide(int num, int den) {
    if (den == 0) {
        throw runtime_error("Division by zero error");
    }
    cout << "Result of division: " << num / den << endl;
}

int main() {
    int numerator = 5, denominator = 0;

    try {
        divide(numerator, denominator);
    } catch (const exception& e) {
        cout << "Error: " << e.what() << endl;
    }

    return 0;
}

Output

Error: Division by zero error

Exception Handling in Java:

1. throw: Used to explicitly generate exceptions in code. For example, throwing an exception when a required parameter is null in a user authentication program.
2. throws: Declares exceptions that might be thrown by a method but are not handled within the method itself. It informs the caller method about potential exceptions that need to be handled.
3. try-catch: Used for exception handling in Java. The code that may throw an exception is enclosed within the try block, and exceptions are caught and handled in the catch block(s).
4. finally: An optional block that follows a try-catch block. It is used for cleanup tasks and always executes, regardless of whether an exception occurred or not.

Java

/*package whatever //do not write package name here */

import java.io.*;

class GFG {
      // Function to throw ArithmeticException
    public static void divide(int num, int den)
        throws ArithmeticException
    {
        if (den == 0) {
            throw new ArithmeticException(
                "Division by zero error");
        }
        System.out.print("Result of division: "
                           + num / den);
    }

    public static void main(String[] args)
    {
        int numerator = 5;
        int denominator = 0;

        try {
            divide(numerator, denominator);
        }
        catch (ArithmeticException e) {
            System.out.print("Error: " + e.getMessage());
        }
        finally {
              System.out.println();
        }
    }
}

Output

Error: Division by zero error

Exception Handling in Python:

In Python, the try-except-finally statement facilitates structured exception handling with three essential components: the try block, the except block, and the finally block.

• try Block: Encloses code where exceptions may occur, anticipating potential errors.
• except Block: Follows the try block and handles exceptions that occur within it, allowing for specific actions based on exception types.
• finally Block: Optional block that follows the try and except blocks, executing code always, typically used for cleanup tasks like releasing resources.

Python3

# Function to throw ZeroDivisionError
def divide(num, den):
    try:
        result = num / den
    except ZeroDivisionError:
        print("Error: Division by zero")
    else:
        print("Result of division:", result)
    finally:
        print("End of division operation")

try:
    numerator = 5
    denominator = 0
    divide(numerator, denominator)
except ValueError:
    print("Error: Invalid input, please enter integers")

Output

Error: Division by zero
End of division operation

Exception Handling in C#:

• Try Block: Encloses code where exceptions may occur.
• Catch Block: Follows the try block and handles exceptions that occur within it.
• Finally Block: Optional block that follows the try-catch block, containing code always executed, typically used for cleanup tasks.

C#

using System;

public class GFG {

    static void Divide(int num, int den)
    {
        try {
            if (den == 0) {
                throw new ArgumentException(
                    "Division by zero error");
            }
            Console.WriteLine("Result of division: "
                              + (num / den));
        }
        catch (ArgumentException e) {
            Console.WriteLine("Error: " + e.Message);
        }
    }

    static void Main()
    {
        try {
            int numerator = 5;

            int denominator = 0;

            Divide(numerator, denominator);
        }
        catch (FormatException) {
            Console.WriteLine("Error: Invalid input, please enter integers.");
        }
    }
}

Output

Error: Division by zero error

Exception Handling in JavaScript:

• try: This is where you put code that might cause an error. If an error happens, the program stops running this block and moves to the catch{} block.
• catch: This block contains code that runs only if an error happened in the try{} block. If the try{} block runs without any errors, the catch{} block is skipped.
• finally: This block contains code that will run no matter what – whether an error happened or not.
• throw: This is used when you want to create your own errors.

JavaScript

function divide(num, den) {
    try {
        if (den === 0) {
            throw new Error("Division by zero error");
        }
        console.log("Result of division:", num / den);
    } catch (error) {
        console.log("Error:", error.message);
    } finally {
        console.log("End of division operation");
    }
}

try {
    let numerator = 5;
    let denominator = 0;

    if (!isNaN(numerator) && !isNaN(denominator)) {
        divide(numerator, denominator);
    } else {
        throw new Error("Invalid input, please enter integers.");
    }
} catch (error) {
    console.log("Error:", error.message);
}

Output

Error: Division by zero error
End of division operation

Exception Handling Best Practices:

• Catch specific exceptions, provide clear error messages, and handle exceptions at the appropriate level
• Use finally blocks for resource cleanup, differentiate between checked and unchecked exceptions, document exception handling, and thoroughly test exception scenarios for robust code.

Conclusion:

In conclusion, exception handling is a crucial aspect of programming that ensures the smooth execution of a program despite the occurrence of errors. It allows for the management of errors in a way that doesn’t disrupt the normal flow of the program, thereby enhancing the robustness and reliability of the software. It’s an essential tool for developers to create error-resistant and efficient programs.