Classes and Objects in C++
practice.

Pick out the correct option.

What is the identifier given to string class to declare string objects?

Which is used to do the dereferencing?

Pick out the correct statement.

What will be the output of the following C++ code?

#include  <iostream>
using namespace std;
int main()
{
    double arr[] = {5.0, 6.0, 7.0, 8.0};
    double *p = (arr+2);
    cout << *p << endl;   
    cout << arr << endl;  
    cout << *(arr+3) << endl;
    cout << *(arr) << endl;  
    cout << *arr+9 << endl;  
    return 0;
}

What will be the output of the following C++ code?

#include <iostream>
#include <string>
using namespace std;
class B
{
	int b;
    public:
	B(){}
	B(int i){
		b = i;
	}
	int show(){
		return b;
	}
};
 
class C
{
	B b;
    public:
	C(int i){
		b = B(i);
	}
	friend void show(){
 
		C c(10);
		cout<<"value of b is: "<<c.b.show()<<endl;
	}
};
 
int main(int argc, char const *argv[])
{
	C c(1);
	c.show();
	return 0;
}

Which is the correct way of concatenating a character at the end of a string object?

way 1:
string s;
s = s + 'a';
 
way 2:
string s;
s.push_back('a');

What will be the output of the following C++ code?

#include <iostream> 
#include <string>
using namespace std; 
int main(int argc, char const *argv[])
{
	string s1 = "Hello";
	string s2 = "World";
	string s3 = s1 + " " + s2;
	cout<<s3;
	return 0;
}

When we are using heap operations what do we need to do to save the memory?

Which method do we use to append more than one character at a time?

What will be the output of the following C++ code?

#include <iostream>
#include <string>
using namespace std;
class Box
{
	int capacity;
    public:
	Box(int cap){
		capacity = cap;
	}
	friend void show();
};
 
void Box::show()
{	
	Box b(10);
	cout<<"Value of capacity is: "<<b.capacity<<endl;
}
 
int main(int argc, char const *argv[])
{
	show();
	return 0;
}

What will be the output of the following C++ code?

#include <iostream>
#include <string>
using namespace std;
int main ()
{
    string str ("steve jobs is legend");
    string::iterator it;
    str.erase (str.begin()+ 5, str.end()-7);
    cout << str << endl;      
    return 0;
}

What will be the output of the following C++ code?

#include <iostream> 
using namespace std;
class A
{
    public:
    int x;
    A(int n = 0) : x(n) {};
    int& operator[](int n)
    {
         cout << "0" ;
         return x;
    }
    int operator[](int n) const
    {
         cout << "1" ;
         return x;
    }
 };
void foo(const A& a)
{
    int z = a[2];
}
int main()
{
    A a(7);
    a[3]  = 8;
    int z = a[2];
    foo(a);
    return 0;
}

What will be the output of the following C++ code?

#include <iostream>
using namespace std;
class Box
{
    double width;
    public:
    friend void printWidth( Box box );
    void setWidth( double wid );
};
void Box::setWidth( double wid )
{
    width = wid;
}
void printWidth( Box box )
{
    box.width = box.width * 2;
    cout << "Width of box : " << box.width << endl;
}
int main( )
{
    Box box;
    box.setWidth(10.0);
    printWidth( box );
    return 0;
}

What will be the output of the following C++ code?

#include <iostream>
using namespace std;
class Complex
{
    private:
    float real;
    float imag;
    public:
    Complex():real(0), imag(0){}
    Complex operator ()(float re, float im)
    {
        real += re;
        imag += im;
        return *this;
    }
    Complex operator() (float re)
    {
        real += re;
        return *this;
    }
    void display()
    {
        cout << "(" << real << "," << imag << ")" << endl;
    }
};
int main()
{
    Complex c1, c2;
    c2 = c1(3.2, 5.3);
    c1(6.5, 2.7);
    c2(1.9);
    cout << "c2=";c1.display();
    cout << "c2=";c2.display();
    return 0;
}

What will be the output of the following C++ code?

#include <iostream>
#include <complex>
using namespace std;
int main()
{
    complex<double> c1(4.0, 3.0);
    complex<float> c2(polar(5.0, 0.75));
    cout  << (c1 += sqrt(c1)) << endl;
    return 0;
}

What does the dereference operator will return?

What will be the output of the following C++ code?

#include <iostream>
#include <string>
using namespace std;
class Box
{
    int capacity;
    Box(){}
    Box(double capacity){
        this->capacity = capacity;
    }
};
int main(int argc, char const *argv[])
{
    Box b1(10);
    Box b2 = Box(14);
    return 0;
}

What will be the output of the following C++ code?

#include <iostream>
#include <string>
using namespace std;
class B
{
	int b;
   public:
	B(){}
	B(int i){
		b = i;
	}
	int show(){
		return b;
	}
};
 
class C
{
	B b;
    public:
	C(int i){
		b = B(i);
	}
	friend void show(){
 
		C c(10);
		cout<<"value of b is: "<<c.b.show()<<endl;
	}
};
 
int main(int argc, char const *argv[])
{
	show();
	return 0;
}

Give the function prototype of the operator function which we need to define in this program so that the program has no errors.

#include <iostream>
#include <string>
using namespace std;
class Box{
    int capacity;
public:
    Box(){}
    Box(double capacity){
	this->capacity = capacity;
    }
};
int main(int argc, char const *argv[])
{
    Box b1(10);
    Box b2 = Box(14);
    if(b1 == b2){
	cout<<"Equal";
    }
    else{
        cout<<"Not Equal";
    }
    return 0;
}