Exception Handling using classes in C++

In this article, we will discuss how to handle the exceptions using classes.

Exception Handling:

• Exceptions are run-time anomalies or abnormal conditions that a program encounters during its execution.
• There are two types of exceptions:
  • Synchronous Exception
  • Asynchronous Exception(Ex: which are beyond the program’s control, Disc failure, etc).
• C++ provides the following specialized keywords for this purpose:
  • try: represents a block of code that can throw an exception.
  • catch: represents a block of code that is executed when a particular exception is thrown.
  • throw: Used to throw an exception. Also used to list the exceptions that a function throws, but doesn’t handle itself.

Problem Statement:

• Create a class Numbers which has two data members a and b.
• Write iterative functions to find the GCD of two numbers.
• Write an iterative function to check whether any given number is prime or not. If found to be true, then throws an exception to class MyPrimeException.
• Define your own MyPrimeException class.

Solution:

• Define a class named Number which has two private data members as a and b.
• Define two member functions as:
  • int gcd(): to calculate the HCF of the two numbers.
  • bool isPrime(): to check if the given number is prime or not.
• Use constructor which is used to initialize the data members.
• Take another class named Temporary which will be called when an exception is thrown.

Below is the implementation to illustrate the concept of Exception Handling using classes:

C++

// C++ program to illustrate the concept
// of exception handling using class

#include <bits/stdc++.h>
using namespace std;

// Class declaration
class Number {
private:
    int a, b;

public:
    // Constructors
    Number(int x, int y)
    {
        a = x;
        b = y;
    }

    // Function that find the GCD
    // of two numbers a and b
    int gcd()
    {
        // While a is not equal to b
        while (a != b) {

            // Update a to a - b
            if (a > b)
                a = a - b;

            // Otherwise, update b
            else
                b = b - a;
        }

        // Return the resultant GCD
        return a;
    }

    // Function to check if the
    // given number is prime
    bool isPrime(int n)
    {
        // Base Case
        if (n <= 1)
            return false;

        // Iterate over the range [2, N]
        for (int i = 2; i < n; i++) {

            // If n has more than 2
            // factors, then return
            // false
            if (n % i == 0)
                return false;
        }

        // Return true
        return true;
    }
};

// Empty class
class MyPrimeException {
};

// Driver Code
int main()
{
    int x = 13, y = 56;

    Number num1(x, y);

    // Print the GCD of X and Y
    cout << "GCD is = "
         << num1.gcd() << endl;

    // If X is prime
    if (num1.isPrime(x))
        cout << x
             << " is a prime number"
             << endl;

    // If Y is prime
    if (num1.isPrime(y))
        cout << y
             << " is a prime number"
             << endl;

    // Exception Handling
    if ((num1.isPrime(x))
        || (num1.isPrime(y))) {

        // Try Block
        try {
            throw MyPrimeException();
        }

        // Catch Block
        catch (MyPrimeException t) {

            cout << "Caught exception "
                 << "of MyPrimeException "
                 << "class." << endl;
        }
    }

    return 0;
}

Output:

GCD is = 1
13 is a prime number
Caught exception of MyPrimeException class.