Lecture 09 Exception Handling(1 ) in c++.pptx

Lecture 09 Exception Handling(1).pptx

1. Object Oriented Programming Exception Handling

2. Exception Handling Exceptions are errors that occur at runtime. They are caused by a wide variety of exceptional circumstance, such as running out of memory, not being able to open a file, trying to initialize an object to an impossible value. The process of handling these exceptions is called exception handling . Using the exception handling mechanism, the control from one part of the program where the exception occurred can be transferred to another part of the code. U sing exception handling in C++, we can handle the exceptions so that our program keeps running.

3. Exception Handling C++ provides an inbuilt feature for Exception Handling . It can be done using the following specialized keywords: try, catch, and throw with each having a different purpose . try { // Code that might throw an exception throw SomeExceptionType ("Error message"); } catch ( ExceptionName e1 ) { // catch block catches the exception that is thrown from try block }

4. #include < iostream > #include < stdexcept > using namespace std ;   int main() {        // try block      try {          int numerator = 10;          int denominator = 0;          int res;            // check if denominator is 0 then throw runtime          // error.          if (denominator == 0) {              throw runtime_error (                  "Division by zero not allowed!" );          }            // calculate result if no exception occurs          res = numerator / denominator;          //[printing result after division          cout << "Result after division: " << res << endl ;      }      // catch block to catch the thrown exception      catch ( const exception& e) {          // print the exception          cout << "Exception " << e.what () << endl ;      }        return 0; } Output Exception Division by zero not allowed!

5. #include <iostream> using namespace std;   int main() {      int x = -1;        // Some code      cout << "Before try \n" ;        // try block      try {          cout << "Inside try \n" ;          if (x < 0) {              // throwing an exception              throw x;              cout << "After throw (Never executed) \n" ;          }      }        // catch block      catch ( int x) {          cout << "Exception Caught \n" ;      }        cout << "After catch (Will be executed) \n" ;      return 0; } Output Before try Inside try Exception Caught After catch (Will be executed)

6. Special Catch block There is a special catch block called the ‘catch-all’ block, written as catch(…), that can be used to catch all types of exceptions.

7. #include < iostream > using namespace std ;   int main() {      // try block      try {            // throw          throw 10;      }        // catch block      catch ( char * excp ) {          cout << "Caught " << excp ;      }        // catch all      catch (...) {          cout << "Default Exception\n" ;      }      return 0; } Output Default Exception

8. C++ Standard Exceptions

9. Standard Exception classes Standard Exception Classes: C ++ provides several standard exception classes, such as std :: runtime_error , std :: logic_error , std :: invalid_argument , etc., which can be used to represent different types of errors.

10. Standard Exception classes

11. Practice Question Write a C++ function named calculateSumOfSquares that takes three parameters of type int. The function should calculate the sum of squares of all the parameters if the following conditions are met : All parameters are different. All parameters are positive. All parameters are odd. If any of these conditions are not met, the function should throw different exceptions : If the parameters are not different, throw an exception with the message "Parameters must be different". If any parameter is not positive, throw an exception with the message "Parameters must be positive". If any parameter is not odd, throw an exception with the message "Parameters must be odd". In the main function : Prompt the user to input three integers. Call the calculateSumOfSquares function with the user-provided integers as arguments. Handle any exceptions thrown by the function and display appropriate error messages. If no exceptions are thrown, display the calculated sum of squares.

12. Exception Handling in classes

13. Exception Handling in classes Consider Book chapter#14 example for Practice.