QUESTION BANK UNIT III

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1 QUESTION BANK UNIT III DEPARTMENT: CSE SUB NAME: OBJECT ORIENTED PROGRAMMING SEMESTER III SUB CODE: CS2203 PART A (2 MARKS) 1. What are templates? (AUC DEC 2009) Template is one of the features added to C++. It is a new concept which enable us to define generic classes and functions and thus provides support for generic programming. A template can be used to create a family of classes or functions. 2. Illustrate the exception handling mechanism. (AUC DEC 2009) C++ exception handling mechanism is basically upon three keywords, namely, try, throw, and catch. try is used to preface a block of statements which may generate exceptions. throw - When an exception is detected, it is thrown using a throw statement in the try block. Catch- A catch block defined by the keyword catch catches the exception thrown by the thrown statement in the try block and handles its appropriately. 3. What happens when a raised exception is not caught by catch block? (AUC MAY 2010) If the type of object thrown matches the arg type in the catch statement, then catch block is executed for handling the exception. If they do not match the program is aborted with the help of abort() function which is invoked by default. When no exception is detected and thrown, the control goes to the statement immediately after the catch block. That is the catch block is skipped. 4. Give the syntax of a pointer to a function which returns an integer and takes arguments one of integer type and 2 of float type. What is the difference between a class and a structure? int (X_fun) (int, float); (AUC MAY 2010) 5. What is a template? What are their advantages (AUC DEC 2010/JUN 2012/DEC 2012) A template can be used to create a family of classes or functions. A template is defined with a parameter that would be replaced by a specified data type at the time of actual use of the class or functions. Supporting different data types in a single framework. The template are sometimes called parameterized classes or functions.

2 6. How is an exception handled in C++? (AUC DEC 2010) Exceptions are run time anomalies or unusual conditions that a program may encounter while executing. 1. Find the problem (Hit the exception) 2. Inform that an error has occurred.( Throw the exception) 3. Receive the error information. ( Catch the exception) 4. Take corrective actions.( Handle the exception) 7. What is function template? Explain. (AUC MAY 2011) Like class template, we can also define function templates that could be used to create a family of functions with different argument types. The general format of a function template is: template <class T> returntype functionname ( arguments of type T) // //.Body of function with type T wherever appropriate //.. 8. List five common examples of exceptions. (AUC MAY 2011) Division by zero Access to an array outside of its bounds Running out of memory or disk space. 9. What is class template? (AUC DEC 2011) Templates allows to define generic classes. It is a simple process to create a generic class using a template with an anonymous type. The general format of class template is: template <class T> class classname // class member specification. //. with anonymous type T wherever appropriate //, What are 3 basic keywords of exception handling mechanism? (AUC DEC 2011) C++ exception handling mechanism is basically built upon three keywords try throw catch 11. What is an exception? (AUC JUN 2012)

3 Exception is defined as unusual error condition occur in a program. 12. What is throw()? What is its use? (AUC DEC 2012) The keyword throw is used to raise an exception when an error is generated in the computation. The throw() expression initializes a temporary object of the type T used in throw ( T arg). throw T 13. Write a function template that swaps the values of the two variable with which it is called? template<class T> T* c; *C = *a; *a = *b; *b = c; (AUC JUN 2013) 14. What functions does terminate and unexpected handlers call? (AUC JUN 2013) The function terminate() is invoked when an exception is raised and the handler not found. The exception unexcepted() is called when a function throws an exception not listed in its exception specification. 15. What is the role of throw and catch blocks? block. throw - When an exception is detected, it is thrown using a throw statement in the try Catch- A catch block defined by the keyword catch catches the exception thrown by the thrown statement in the try block and handles its appropriately. 16. Write a program to exchange values of two variables. Use template variable as function arguments. #include < iostream.h> Using namespace std; Template<class T> Void swap(t &x, T &y) T temp= x; x=y; y= temp; void fun( int m, int n) cout<< m and n before swap: <<m<<n; swap(m,n); cout<< m and n after swap: <<m<<n;

4 int main() fun(100,200); return 0; Output m and n before swap: m and n after swap: Distinguish between overloaded functions and function templates overloaded functions A template function may be overloaded either by template functions or ordinary functions of its name. function templates Used to create a family of functions with different argument types. No automatic conversions are applied to arguments on the template functions. Template functions can be overloaded. Use multiple parameters in both the class and function templates. A function generated from a function template is called a template function. 18. When do we need multiple catch Handlers? Due to mismatch, if an exception is not caught, abnormal program termination will occur. It is important to note that the catch block is simply skipped if the catch statement does not catch an exception. It is possible that a program segment has more than one condition to throw an exception. In such cases, we can associate more than one catch statement with a try 19. Write a program to demonstrate the concept of rethrowing an exception. #include <iostream.h> Using namespace std; Void divide(double x, double y) cout<< Inside function ; try if(y==0.0) throw y; else cout<< Division= <<x/y; catch(double) cout<< Caught double inside function ; throw; cout<< end of function ; Int main() cout<< Inside main ; try divide(10.5, 2.0); divide(20.0, 0.0) // throwing double // Rethrowing double

5 catch(double) cout<< Caught double inside main ; cout<< end of main ; return 0; 20. What is the need for template function in c++? What are the advantages? C++ supports a mechanism known as template to implement the concepts of generic programming. Templates allows us to generate a family of classes or functions to handle different data types. Templates are very helpful in achieving software reusability. 21. Distinguish between generic and non-generic arguments to function templates. Generic arguments Use more than one generic data type in the template statement, using a comma- separated list. template<class T1,class T2, > returntype functionname (arg of types T1,T2, )..(body of function) Non-generic arguments Use non-type arguments such as strings, function names, constant expressions and built-in-types. template< class T, int size) class array T a[size];//automatic array initialization; 22. Give few examples of multi arguments templates Use more than one generic data type in the template statement,using a commaseparated list. template<class T1,class T2, > returntype functionname (arg of types T1,T2, ).. (body of function) 23. What is terminate() function? Why is it need? The function to call when the exception handling mechanism does not get any proper handler for a thrown exception. If the type of object thrown matches the arg type in the catch statement, then catch block is executed for handling the exception. If they do not match the program is terminated with the help of terminate() function which is invoked by default. 24. What are exception specifications? It is possible to specify what kind of exceptions can be thrown by functions, using a specific syntax. We can append the function definition header with throw keyword and possible type of expressions to be thrown in the parenthesis. It is known as exception specification. Example: void ExGen() throw(int, char) Exception specification is used for throwing outside the function.

6 25. What is unexpected() function?give an example. Like terminate() function, we have our own Unexpected() function. It is possible to check if the exception is already thrown when we are about to throw using Uncaught_exception. This is important as throwing a new exception when one is already thrown call terminate(). 26.What is uncaught_exception() function? And why do we need it? The function to call when we want to check before throwing any exception if some other exception is already on. 27.What is the disadvantage of exception handling function? It adds to runtime overhead. Demands different style of programming than conventional programming. It is not the tool to replace normal error handling. 28. What is the object destroy problem? And how can exception handling help here? The objects which are created just before the error has occurred must be destroyed properly. This is known as the object destroy problem. 29. What is typename? The keyword typename indicates that the expression following the keyword is the name of a type. Used within the body of the template function<> Writing typename before, the compiler makes the program more portable. 30.Give an example explaining the need for overloading a template with another template. The template function definition forces the compiler to overload the function as many times as it is used with different types in the program. A template function may be overloaded either by template functions or ordinary functions of its name. 31. What is the importance of catch all? It is possible for us to catch all types of exceptions in a single catch section. We can use catch( )( three dots as argument) for the same. Catch all section is very useful in debugging and is as useful as a default statement in switch. 32. What is the difference between manually overloaded functions and template instantiation? manually overloaded functions Automatically overloadable functions have different types of arguments but same body. Usually have different code. template instantiation The process of creating a specific class from a class template is called instantiation. The template function requires an exact match of arguments. 33. Give an example where using the default arguments are useful in class template. Example: template<typename Type= int, int Size=10>

7 PART B (16 MARKS) 1. (i) Write the syntax for member function template. (4) (AUC DEC 2009) The member function of the template classes themselves are parameterized by the type argument and therefore these functions must be defined by the function templates. It takes the following general form: Template<class T> returntype classname <T> :: functionname(arglist) //. // Function body //.. (ii) Write a C++ program using class template for finding the scalar product for int type vector and float type vector. (12) (AUC DEC 2009) #include<iostream.h> Using namespace std; Const size = 3; Template<class T> Class vector T *v; public: vector() v=new T[size]; for(int i=0;i<size;i++) v[i]=0; Vector(T* a) // create a vector from an array. for(int i=0;i<size;i++) v[i]=a[i]; T operator* (vector &y) // scalar product T sum = 0; for(int i=0;i<size;i++) sum += this -> v[i] * y.v[i]; return sum; Void display(void) for(int i=0;i<size;i++) cout<<v[i]<< \t ; ; int main() int x[3] = 1,2,3; int y[3] = 4,5,6; float a[3] = 1.1,2.2,3.3; float b[3] = 4.4,5.5,6.6; vector <int> v1; vector <int> v2; vector <float> v3; vector <float> v4; v1 = x; v2 = y; v3 = a; v4 = b; cout<< v1= ; v1.display(); cout<< v2= ; v2.display(); cout<< v3= ; v3.display(); cout<< v4= ; v4.display(); cout<< v1 x v2 = << v1*v2;

8 cout<< v3 x v4 = <<v3 x v4; return 0; SAMPLE OUTPUT v1 = v2 = v3 = v4 = v1 x v2 = 32 v3 x v4 = (i) Explain how rethrowing of an exception is done. (4) (AUC DEC 2009) A handler may decide to rethrow the exception caught without processing it. In such situations, we may simply invoke throw without any arguments as shown below : throw; This causes the current exception to be thrown to the next enclosing try/catch sequence and is caught by a catch statement listed after that enclosing try block. When an exception is rethrown, it will not be caught by the same catch statement or any other catch in that group. Rather, it will be caught by an appropriate catch in the outer try/catch sequence only. A catch handler itself may detect and throw an exception. The exception thrown will be caught by any catch statements in that group. It will be passed on to the next outer try/catch sequence of processing. (ii) Write a C++ program that illustrates multiple catch statements. (12) (AUC DEC 2009) It is possible that a program segment has more than one condition to throw an exception. In such cases, we can associate more than one catch statement with a try(like switch statement). Program: #include<iostream.h> Using namespace std; Void test(int x) try If( x == 1) throw x; // int else if( x==0) throw x ; // char else if(x == -1) throw 1.0; // double cout<< End of try-block ; catch(char c) // catch 1 Cout<< Caught a character ; catch(int m) //catch 2 Cout<< Caught an integer ; catch(double d) // catch 3 Cout<< Caught a double ; cout<< End of try-catch system \n ; int main() cout<< Testing Multiple catches ; cout<< X == 1 \n ;

9 test(1); cout<< x == 0 \n ; test(0); cout<< x == -1 \n ; test(-1); cout<< x == 2 \n ; test(2); return 0; SAMPLE OUTPUT Testing Multiple Catches X ==1 Caught an integer End of try-catch system X == 0 Caught a character End of try-catch system X == -1 Caught a double End of try-catch system X == 2 End of try-block End of try-catch system 3. Write a C++ program to create a base class called house. There are two classes called door and window available. The house class has members which provide information related to the area of construction, doors and windows details. It delegates responsibility of computing the cost of doors and window construction to door and window classes respectively. Write a C++ program to model the above relationship and find the cost of constructing the house. (16) (AUC MAY 2010) #include<stdio.h> class house int size, c; public: void read() cin>>size; int cost() c=size * 1000; return(c); ; class window :: public house

10 int no_of_window,c; public: void get() cin>>no_of_window; int wincost() c=no_of_window x 500; ; class door :: public window int no_of_door,d; public: void getdata() cin>>no_of_door; int doorcost() d=no_of_door * 600; ; int main() door d1; int c; d1.read(); d1.wincost(); d1.doorcost(); c=cost()+wincost()+doorcost(); cout<<c; 4. Write a C++ program to compute the square root of a number. The input value must be tested for validity. If it is negative, the user defined function mysqrt() should raise an exception. (AUC MAY 2010) #include<iostream.h> #includte<math.h>

11 main() int a; float n; cin>>a; try n=mysqrt(a); catch float(negative) cout<< the no.of negative is: ; float mysqr(int a) float n; if(a>0) throws n; else return n=sqrt(a); 5. (i) Explain the overloading of template function with suitable example. (8) (AUC DEC 2010) A template function may be overloaded either by template functions or ordinary functions of its name. In such cases, the overloading accomplishes as follows: 1. Call an ordinary function that has an exact match. 2. Call a template function that could be created with an exact match. 3. Try normal overloading resolution to ordinary functions and call the one that matches. An error is generated if no match is found. No automatic conversions are applied to arguments on the template functions. Program: Template function with Explicit function #include<iostream.h> #include<string.h> Using namespace std; Template<class T> void display(t x) // Overloaded template function display cout<< Overloaded Template Display 1 : <<x<< \n ;

12 cout<< Overloaded Template Display 2 : <<x<<,<<y<< \n ; void display(int x) // Overloaded generic display function cout<< Explicit Display: <<x<< \n ; int main() display(100); display(12.34); display(100,12.34); display( C ); return 0; SAMPLE OUTPUT Explicit Display: 100 Overloaded template Display 1: Overloaded template Display 2: 100, Overloaded template Display 1: C ii) Write a function template for finding the minimum value contained in an array. (8) (AUC DEC 2010) Program: Template< Class T> T minimum ( T A, T n) T a[]; T min = 1; for(int i=0; i<n; i++) if(a[i]<=min) min=a[i]; return min; void main() int a[10], n ; min; cin>>n; for(int i=0;i<n;i++) cin>>a[i]; min=minimum (a,n); cout<<min; 6. (i) List the advantages of exception handling mechanisms. (4) (AUC DEC 2010)

13 C++ exception provides a type-safe, integrated approach, for coping with the unusual predictable problems that arise while executing a program. Exception handling mechanism is to provide means to detect and report an exceptional circumstances. The mechanism suggests a separate error handling code. Easily we can detect errors and throw exceptions. (ii) Write a C++ program for the following.(12) (AUC DEC 2010) (1) A function to read two double type numbers from keyboard. (2) A function to calculate the division of these two numbers. (3)A try block to throw an exception when a wrong type of data is keyed in. (4) A try block to detect and throw an exception if the condition divide by zero occurs. (5)Appropriate catch block to handle the exceptions thrown. Ans: // Divide operation validation ( divide-by-zero) #include<iostream.h> class number int num; public: void read() cin>>num; class DIVIDE ; //abstract class used in exceptions int div(number num2) if(num2.num == 0) throw DIVIDE(); else return num/num2.num; ; int main() number num1,num2; int result; num1.read(); num2.read(); try cout<< trying division operator ; result=num1.div(num2); cout<< Succeeded ; catch(number:: DIVIDE) //actions taken in response to exception cout<< failed ; cout<< Exception divide-by-zero ; return1; //no exceptions; display result; cout<< num1/num2 = <<result; result 0; 7. Explain with an example, how exception handling is carried out in C++. (8) (AUC MAY 2011)

14 C++ exception handling mechanism is basically upon three keywords, namely, try, throw, and catch. try is used to preface a block of statements which may generate exceptions. throw - When an exception is detected, it is thrown using a throw statement in the try block. Catch- A catch block defined by the keyword catch catches the exception thrown by the thrown statement in the try block and handles its appropriately. The block throwing exception The catch block that catches an exception must immediately follow the try block that throws the exception. The general form of these two blocks are as follows: try.. throw exception;. catch (type arg).. //Block of statements detects and throws an exception // catches exception // block of statement that handle the exception When the try block throws an exception, the program control leaves the try block and enters the catch statement of the catch block. If the type of object thrown matches the arg type in the catch statement, then catch block is executed for handling the exception.

15 If they do not match the program is aborted with the help of abort() function which is invoked by default. When no exception is detected and thrown, the control goes to the statement immediately after the catch block. That is the catch block is skipped. 8. (i)write a class template to implement a stack. (10) (AUC MAY 2011) #include<iostream.h> using namesace std; template <typename ElementType> class Stack private: int Stackpointer; ElementType StackArray[10]; public: Stack() Stackpointer = 0; void push(elementtype value) if(stackpointer == 9) cout<< Stack Overflow! can t insert! ; else StackArray[Stackpointer] = value; Stackpointer++; ElementType pop() if(stackpointer == 0) cout<< Stack Underflow, can t pop ; else Stackpointer--; return StackArray[Stackpointer]; ;

16 void main() Stack < int> MyStack; MyStack.push(1); MyStack.push(2); cout<<mystack.pop()<< \n ; cout<<mystack.pop()<< \n ; Stack <char> YourStack; YourStack.pop( n ); YourStack.pop( o ); cout<<yourstack.pop()<< \n ; cout<<yourstack.pop()<< \n ; (ii) What is a user defined exception? Explain with an example. (6) (AUC MAY 2011) Answer: //Uncaught exception invokes abort() #include<iostream.h> class except1 ; class except2 ; void main() try cout<< Throwing uncaught exception <<endl; throw except2(); catch(except1) //true if throw except is executed in city scope cout<< Exception1 ; // except2 is not caught hence, program aborts //here without proceeding further cout<< Not displayed ; 9. (i)define a DivideBy Zero definition and use it to throw exceptions on attempts to divide by zero (8) (AUC MAY 2011) Program detects and catches a division-by-zero problem. The output of the first run shows a successful execution. When no exception is thrown, the catch block is skipped and execution resumes with the first line after the catch. In the second run, the denominator x becomes zero and therefore a division-by-zero situation occurs. Program: #include<iostream.h> using namespace std; int main() int a,b; cout<< Enter values of a and b ; cin>>a; cin>>b; int x = a-b;

17 try if(x!=0) cout<< Result (a/x) = << a/x << \n ; else // There is an exception throw(x); //Throws int object catch(int i) // Catches the exception cout<< Exception caught: DIVIDE BY ZERO \n ; cout<< END ; return 0; SAMPLE OUTPUT First run Enter values of a and b Result (a/x) = 4 END Second run Enter values of a and b Exception caught: DIVIDE BY ZERO END (ii)write a C++ program to demonstrate function template to print array of different types. (8) (AUC DEC 2011) Answer: #include<iostream.h> template<class T> void print (T a) for(int i=0;i<10;i++) cout<<a[i]; void main() int i; int a[10]; float b[10]; char c[10]; for(i=0;i<10;i++) cin>>a[i]; print (a); for(i=0;i<10;i++)

18 cin>>b[i]; print (b); cin>>c; print(c); 10. (i)describe class template with suitable example? (AUC DEC 2011) Refer Part B question number 1(ii) and 8(i) (ii)explain exception handling in C++ with suitable example? (AUC DEC 2011) Refer Part B question number 7(i) and 9.(i) 11. Give the syntax for function template. Write template function for bubble sort. Write a test program to illustrate its use. (AUC JUN 2012) Templates support generic programming which allows to develop reusable software components such as functions, classes,etc; Supporting different data types in a single framework. A template in C++ allows the construction of a family of template functions and classes to perform the same operation on different data types. The template declared for functions are called function templates and those declared for classes are called class templates. Like class template, we can also define function templates that could be used to create a family of functions with different argument types. The general format of function template is, template<class T> returntype functionname ( arguments of type T) // Body of function with type T wherever appropriate. The function template syntax is similar to that of the class template except that we are defining functions instead of classes. Program #include<iostream.h> using namespace std; template<class T> void bubble(t a[], int n) for(int i=0;i<n-1;i++) for(int j=n-1;i<j;j--) if(a[j] < a[j-1]) swap(a[j],a[j-1]); // Calls template function template<class X>

19 void swap(x &a, X &b) X temp = a; a=b; b = temp; int main() int x[5] = 10,50,30,40,20; float y[5] = 1.1,5.5,3.3,4.4,2.2; bubble(x,5); // Calls template functions for int values bubble(y,5); // Calls template functions for float values cout<< Sorted x-array ; for(int i=0;i<5;i++) cout<< x[i]<< ; cout<< endl; cout<< Sorted y-array: ; for(int j=0;j<5;j++) cout<<y[j]<< ; cout<<endl; return 0; OUTPUT: Sorted x-array : Sorted y-array : Discuss in detail about exception handling constructs and write a program to illustrate divide by zero exception.(16) (AUC JUN 2012/ DEC 2012) Answer: Exceptions refer to unusual conditions in a program. The unusual conditions could be faults, causing an error which it turn causes the program to fail. The error handling mechanism of C++ is generally reffered to as exception handling. It provides a straightforward mechanism for adding reliable error handling mechanism in a program. Exceptions are classified into two types. (i) Synchronous (ii) Asynchronous Synchronous The exceptions which occur during the program execution, due to some fault in the input-data or technique that is not suitable to handle the current class of data, within the program, are known as synchronous exceptions. Asynchronous Errors such as out-of-range, overflow, underflow and so on belong to the class of asynchronous exception. Refer PART-B question number 7(i) and 9(i) 13. Write a program for binary search as a generic function. The function should take arguments as array name, the size and element to be searched. (AUC DEC 2012) Answer: Binary search function template<typename T, typename compare_less> static int binary_search( QList<T>* list,t target)

20 int low=0; int high= list->count() -1; while( low<=high) int middle = low+ (high low)/2; if( compare_less(*target, *list[middle])) high = middle 1; else if ( Compare_less(*list[middle],*target)) low=middle + 1; else return middle; 14. Write a class template to generate a class Matrix automatically for a matrix of any particular type. Using the class template definition, the program should handle the arithmetic operations (+, -, *, /) for any particular type.(such as int, float, double, char) (AUC JUN 2013) Answer: #include<iostream.h> #include<conio.h> template<class T> class matrix T x[3] [3]; public: void getmatrix(); void showmatrix(); void addition(matrix<t>); void subtraction(matrix<t>); viod multiplication(matrix<t>,matrix<t>); ; template<class T> void matrix<t>::getmatrix() int i,j; cout<< enter values of amatrix ; for(i=0;i<3;i++) for(j=0;j<3;j++) cin>>x[i] [j]; template<class T> void matrix<t>::showmatrix() int i,j; cout<< matrix is ; for(j=0;j<3;j++)

21 cout<< \t <<x[i][j]; template<class T> void matrix<t>::addition(matrix<t> b) int i,j; for(i=0;i<3;i++) for(j=0;j<3;j++) x[i][j]=x[i][j]+b.x[i][j]; template<class T> void matrix<t>::subtraction(matrix<t> b) int i,j; for(i=0;i<3;i++) for(j=0;j<3;j++) x[i][j]=x[i][j]-b.x[i][j]; template<class T> void matrix<t>::multiplication(matrix<t> b, matrix<t> a) int i,j,k; for(i=0;i<3;i++) for(j=0;j<3;j++) x[i][j]=0; for(i=0;i<3;i++) for(j=0;j<3;j++) for(k=0;k<3;k++) x[i][j]=x[i][j]+(a.x[i][k]*b.x[k][j]); void main() int ch; matrix<int>a1,b1,c1; matrix<float>a2,b2,c2; clrscr(); do

22 cout<< \n\t 1> Addition (int) ; cout<< \n\t 2> Subtraction (int) ; cout<< \n\t 3> Multiplication(int) ; cout<< \n\t 4> Addition (float) ; cout<< \n\t 5> Subtraction (float) ; cout<< \n\t 6> Multiplication(float) ; cout<< \n\t enter your choice ; cin>>ch; switch(ch); case 1: a1.getmatrix(); a1.showmatrix(); b1.getmatrix(); b1.showmatrix(); a1.addition(b1); a1.showmatrix(); break; case 2: a1.getmatrix(); a1.showmatrix(); b1.getmatrix(); b1.showmatrix(); a1.subtraction(b1); a1.showmatrix(); break; case 3: a1.getmatrix(); a1.showmatrix(); b1.getmatrix(); b1.showmatrix(); a1.multiplication(b1,a1); a1.showmatrix(); break; case 4: a2.getmatrix(); a2.showmatrix(); b2.getmatrix(); b2.showmatrix(); a2.addition(b2); a2.showmatrix(); break; case 5: a2.getmatrix(); a2.showmatrix(); b2.getmatrix(); b2.showmatrix(); a2.subtraction(b2); a2.showmatrix(); break;

23 case 6: a2.getmatrix(); a2.showmatrix(); b2.getmatrix(); b2.showmatrix();c2.multiplication(b2,a2); c2.showmatrix(); break; while(ch!=7); getch(); 15. Explain the following concepts with example. (AUC JUN 2013) (i) try-catch-throw paradigm (ii) Exception Specification Refer Part-B question number 6(i), 7(i) and 9(i), Part-A question number Write a program 1. to show how to restrict the types of exceptions that can be thrown by a function. Refer Part-B question number 9.(i) 2. to show how to rethrow an exception. Refer Part A question number 15 and Part B question number 2(i).