Exception Handling

Exception is defined as an event that occurs during the execution of a program that is unexpected by the program code. The actions to be performed in case of occurrence of an exception is not known to the program. In such a case, we create an exception object and call the exception handler code. The execution of an exception handler so that the program code does not crash is called Exception handling. Exception handling is important because it gracefully handles an unwanted event, an exception so that the program code still makes sense to the user.

Syntax
try {
    //Code to try
    throw exception; // Throw an exception when a problem arise
}
catch () {
    // Block of code to handle errors
}

CODE

EG 1 . Handling Exception

#include <iostream>
using namespace std;

int main() {
    try {
        int num1, num2;
        cout << "Enter Number 1 : ";
        cin >> num1;
        cout << "Enter Number 2 : ";
        cin >> num2;
        if (num2 == 0) throw 1;
        cout << num1 / num2 << endl;
    }
    catch(int thrownValue) {
        cout << "Attempted to divide by 0" << endl;
    }
}

CODE EXPLANATION
In the above code, we are getting 2 values from user called num1 and num2. The goal is so simple, we need to divide num1 by num2. Here if user enters num2 value as 0, answer will be infinity. System cannot handle infinity so here we'll get an unhandled exception. In order to handle this, even before doing division operation we are checking whether num2 value is 0 or not. If it is 0, system will throw exception. The moment system executed throw, system will not proceed furthur codes in try, it will jump to catch and execute whatever code we written inside. Now the thrown 1 value will be stored inside thrownValue variable in catch. If we want to use thrownValue we can use it or else we can simply leave as it is. If no error occurs(Eg : if num1 is 4 and num2 is 2, answer will be 0) division operation will takes place and catch block will be skipped.