Question

TOE

B.2 - 30 pts class Student public Student(0 cout <<"Student0, constructor called." << endl; explicit Student string stuName): stuName(stuName) cout << "Student stuName), constructor called." << endl; -Student) cout<-Student0, destructor called." << endl; string getName) return this->stuName void sayHi0 cout<< "Student: Hi!" << endl 4 virtual void sayHello0 cout <<"Student: Hello!" << endl private string stuName "Student" 5 class CSStudent: public Student f public CSStudent0 0 explicit CSStudent string stuName) -CSStudent) Student) 0 6 cout<<"-CSStudent), destructor called."<<endl; void sayHello) cout<<"CSStudent: Hello!" <<endl; class CSStudent340 : public CSStudent public CSStudent3400 cout << "CSStudent3400, constructor called." < endl; 8 explicit CSStudent340(string stuName): CSStudent(stuName) cout<<"CSStudent340(stuName), constructor called." <endl; void sayHi0 cout< "CSStudent340: Hil" << endl; int main Student stuM "Chip" cout << "Stu: "stuM.getName()<endl; stuM.sayHi0) 10 unique ptrcCSStudent stuf make_uniquecCSStudent340(Dale") ) stu->sayHi0:; stu->sayHello0 return 0; This program outputs 10 lines. What are they? Why?

Answer 1

outputs are:

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Student(stuName),constructor called.
Stu:Chip
Student:Hi!
Student(), constructor called.
CSStudent340(stuName),constructor called.
Student:Hi!
CSStudent:Hello!
~CSStudent(), destructor called.
~Student(), destructor called.
~Student(), destructor called.

expilcit keyword before a constructor is used because to avoid implicit conversions.Otherwise compiler does implicit conversion.It also avoids accidental construction that can hide bugs.

EXPLAINATION FOR EACH LINE OF OUTPUT:

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1.Since it is parent class object, and there is a string argument the explicit constructor is called i.e. the second one is called.

2.Since get name is called this line has come.

3.since Sayhi() is called this line has come.

4.Since stu is a derived class object first parent class constructor is invoked and in order all constructors are invoked.

So 1st Student class default constructor is invoked.

5.Next since Cssstudent(name) constructor doesn't have anything nothing is displayed.So Cssstudent340 constructor(not the default one i.e. parameterized) is invoked now.

6.next SayHI of CSSstudent340 is called.

7.say Hello of parent i.e cssstudent is called as csstudent340 doesn't have this method.

8.destructor are first called for child class objects so destructor of csstudent340 is called now.

9,10 parent class destructor are called for both the created objects..