C++ Programming Midterm Exam (3)

Midterm Exam (3)
C++ Programming
NCNU CSIE

Date: May 27th, 2009
Time: 14:10-16:10
Open book; turn off computer & mobile phone

Determine whether the following code has syntax errors or not. If it is correct, predict its output. If it is incorrect, point out the mistake(s).

// Class
#include <iostream>
using std::cout;

class CRectangle
{
        int left;
        int top;
        int right;
        int bottom;
public:
        CRectangle(int l, int t, int r, int b) : left(l), top(t), right(r), bottom(b) {}
        int Area() { return (right-left) * (bottom - top); }
};

int main()
{
        CRectangle R1(0,0,10,20);
        CRectangle R2 = R1;
        cout << R2.Area();
}

Determine whether the following code has syntax errors or not. If it is correct, predict its output. If it is incorrect, point out the mistake(s).

// Static member of a class
#include <iostream>
using std::cout;

class CList
{
public:
        static int count;
        void Inc() { count++; }
        void Dec() { count--; }
};

int main()
{
        CList L2;
        L2.count = 527;
        L2.Inc();
        cout << L2.count << "\n";
}

Determine whether the following code has syntax errors or not. If it is correct, predict its output. If it is incorrect, point out the mistake(s).

// const Object of a Class
#include <iostream>
using std::cout;

class CBox
{
public:
        int volume;
};

int Compare(CBox B1, CBox& B2)
{
        return (B1.volume > B2.volume);
}

int main()
{
        const CBox cigar;           cigar.volume = 10;
        CBox chocolate; 	chocolate.volume = 20;
        if (Compare(cigar, chocolate))
               cout << "cigar is larger.\n";
        else
               cout << "chocolate is larger than or equal to cigar.\n";
}

Determine whether the following code has syntax errors or not. If it is correct, predict its output. If it is incorrect, point out the mistake(s).

// Copy Constructor
#include <iostream>
using std::cout;

class CBox
{
public:
        int volume;
        char* color;
        CBox(int v, char* c = "Violet"): volume(v)
        {
                color = new char[strlen(c)];
                strcpy(color, c);
        }
};

int main()
{
        CBox cigar(10);
        CBox chocolate(cigar);
        strcpy(chocolate.color, "Cyan");
        cout << chocolate.color << "\n";
}

Determine whether the following code has syntax errors or not. If it is correct, predict its output.If it is incorrect, point out the mistake(s).

#include <iostream>
using std::cout;

class CBox
{
public:
        int volume;
        CBox() { volume = 10; }
};

class CContainer : private CBox
{
        char* color;
public:
        CContainer()
        {
                volume = 20;
                color = new char[strlen("Violet")];
                strcpy(color, "Violet");
        }

        CContainer(CContainer& b)
        {
                color = new char[strlen(b.color)];
                strcpy(color, b.color);
        }

        void ShowVolume()
        {
                cout << volume << "\n";
        }
};

int main()
{
        CContainer cigar;
        CContainer chocolate(cigar);
        chocolate.ShowVolume();
}

Determine whether the following code has syntax errors or not. If it is correct, predict its output. If it is incorrect, point out the mistake(s).

// Operator Overloading
#include <iostream>
using std::cout;

class CList
{
public:
        int count;
        CList(int i) : count(i) {}
        CList operator++() { count+=2; return *this; }
        CList operator++(int) { count+=10; return *this; }
};


int main()
{
        CList L2(5);
        L2++;
        cout << L2.count << "\n";
}

Determine whether the following code has syntax errors or not. If it is correct, predict its output. If it is incorrect, point out the mistake(s).

// Access Control Under Inheritance
#include <iostream>
using std::cout;

class John
{
protected:
        int money;
public:
        John(int i) : money(i) {}
};

class Johnson : public John
{
public:
        Johnson(int i) : John(i) {}
        void Show() { cout << money << "\n"; }
};

int main()
{
        Johnson(1500);
        Johnson.Show();
}

Determine whether the following code has syntax errors or not. If it is correct, predict its output. If it is incorrect, point out the mistake(s).

// Friendship
#include <iostream>
using std::cout;

class CBox
{
private:
        int volume;
public:
        CBox(int i) : volume(i) {};
friend int main();
};

int main()
{
        CBox b1(10);
        cout << b1.volume << "\n";
}

Determine whether the following code has syntax errors or not. If it is correct, predict its output. If it is incorrect, point out the mistake(s).

// Virtual Function
#include <iostream>
using std::cout;
using std::endl;

class Animal
{

public:
        int weight;
        Animal(int w = 5) : weight(w) {} ;
        int Cost() { return weight; }
        void ShowCost() { cout << Cost() << "\n"; }
};

class Wolf : public Animal
{
public:
        Wolf() : Animal() {} ;
        int Cost() { return weight * 2 ; }
};

int main()
{
        Wolf a1;
        a1.ShowCost();
}

If we replace the OnDraw() function in P.715 as below, what result will be shown on the screen after you run the program?

void CSketcherView::OnDraw(CDC* pDC)
{
        CSketcherDoc* pDoc = GetDocument();
        ASSERT_VALID(pDoc);
        if (!pDoc)
                return;

        pDC->Ellipse(50,0, 150, 100);
        pDC->Ellipse(0,50, 100, 150);
        pDC->Ellipse(50,100, 150, 200);
        pDC->Ellipse(100, 50, 200, 150);
        pDC->Rectangle(50, 50, 150, 150);

}

If we replace the OnDraw()function in P.715 as below, what result will be shown on the screen after you run the program?

void CSketcherView::OnDraw(CDC* pDC)
{
        CSketcherDoc* pDoc = GetDocument();
        ASSERT_VALID(pDoc);
        if (!pDoc)
                return;

        CBrush* pOldBrush = static_cast<CBrush*>( pDC->SelectStockObject(NULL_BRUSH) );
        int i;
        int x0 = 100;
        int y0 = 100;
        for (i=1; i<10; i++)
                pDC->Rectangle(x0-i*10,y0-i*10,x0+i*10,y0+i*10);

}

Midterm Exam (3) C++ Programming NCNU CSIE

Midterm Exam (3)
C++ Programming
NCNU CSIE