Object Oriented Programming - Old Questions

11. Explain how exceptions are used for handling C++ error in a systematic and OOP-oriented way with the design that includes multiple exceptions.

Exceptions are run-time anomalies or abnormal conditions that a program encounters during its execution. Exception Handling in C++ is a process to handle runtime errors. We perform exception handling so the normal flow of the application can be maintained even after runtime errors. In C++, we use 3 keywords to perform exception handling: try, catch, and throw

• The try statement allows us to define a block of code to be tested for errors while it is being executed.
• The throw keyword throws an exception when a problem is detected, which lets us create a custom error.
• The catch statement allows us to define a block of code to be executed, if an error occurs in the try block.

Syntax to handle multiple exceptions:

try

{

    //protected code

} catch(exceptionName e1)

{

    // catch block

} catch(exceptionName e2)

{

    // catch block

} catch(exceptionName en)

{

    // catch block

}

Example:

#include<iostream.h>
       #include<conio.h>
       void main()
       {
            int a=2;
              try
              {

                  if(a==1)
                      throw a;                  //throwing integer exception

                  else if(a==2)
                      throw 'A';                //throwing character exception

                  else if(a==3)
                      throw 4.5;                //throwing float exception

              }
              catch(int a)
              {
                  cout<<"\\nInteger exception caught.";
              }
              catch(char ch)
              {
                  cout<<"\\nCharacter exception caught.";
              }
              catch(double d)
              {
                  cout<<"\\nDouble exception caught.";
              }
              cout<<"\\nEnd of program.";
       }
   Output :
              Character exception caught.
              End of program.