科目： 程式設計
 學號： 考試日期 2025.6.6
期末考 姓名：
 考試時間 14:10-17:00
Open book; turn off computer & mobile phone
1
6
2
7
3
8
4
9
5
10

  1. (10%) Which of the following is a valid template declaration?
    1. template<T> void func(T x){}
    2. template<class T> T func(x){}
    3. template<typename T> func(T x){}
    4. template<typename T> void func(T x){}

  2. (10%) In Visual C++, when I am designing an MFC application, if I want to create an event handler OnLButtonDown() to handle the event when the mouse left button is down, which tab in the Properties Windows should I navigate to find the corresponding Windows Message to create the event handler?
    Properties Window

  3. (10%) Determine whether the following code has syntax errors or not.  If it is correct, predict its output.  If it is incorrect, point out the line(s) with syntax mistake(s).

    // Callback Function and Overloading Operator<<
    #include <iostream>
    #include <cstdlib>
    using std::ostream;

    class Rational {
    public:
        int numerator;
        int denominator;
        Rational(int n=0, int d=1): numerator(n), denominator(d) {}
    };

    int comp(const void* p1, const void* p2) {
        const Rational a1 = *(static_cast<const Rational*>(p1));
        const Rational a2 = *(static_cast<const Rational*>(p2));
        return a2.numerator*a1.denominator - a1.numerator*a2.denominator;
    }

    ostream& operator<<(ostream& o, const Rational& a) {
        o << a.numerator;
        if (a.denominator != 1)
            o << '/' << a.denominator;
        return o;
    }

    int main() {
        Rational A[] = { Rational(1, 1), Rational(1, 2), Rational(1, 3),
                         Rational(2), Rational(3) };
        qsort(A, sizeof(A)/sizeof(A[0]), sizeof(A[0]), comp);
        for (size_t i=0; i<sizeof(A)/sizeof(A[0]); ++i)
            std::cout << A[i] << ' ';
        return 0;
    }

  4. (10%) Determine whether the following code has syntax errors or not.  If it is correct, predict its output.  If it is incorrect, point out the line(s) with syntax mistake(s).

    // Binary Tree
    #include <iostream>
    class CNode {
    public:
        int value;
        CNode* left;
        CNode* right;
        CNode(int v): value(v), left(nullptr), right(nullptr) {}
        void Print() {
            if (right)
               right->Print();
            std::cout << value;
            if (left)
               left->Print();
        }
        void Insert(int v) {
            if (v < value) {
               if (left)
                   left->Insert(v);
               else
                   left = new CNode(v);
            } else {
                if (right)
                    right->Insert(v);
                else
                    right = new CNode(v);
            }
        }
    };

    class CTree {
    public:
        CNode* root;
        CTree() { root = nullptr; }
        void Print() { root->Print(); }
        CTree& Insert(int v) {
            if (root)
                root->Insert(v);
            else
                root = new CNode(v);
            return *this;
        }
    };

    int main() {
        CTree t;
        t.Insert(3).Insert(1).Insert(2).Insert(5).Insert(4);
        t.Print();
        std::cout << std::endl;
        return 0;
    }
  5. (10%) Determine whether the following code has syntax errors or not.  If it is correct, predict its output.  If it is incorrect, point out the line(s) with syntax mistake(s).

    // Destructor
    #include <iostream>

    class CInt {
    public:
        int value;
        CInt(int v): value(v) { std::cout << "Constructor for " << value << std::end                                                               l;}
        ~CInt() { std::cout << "Destructor for " << value << std::endl; }
    };

    class CRational {
        CInt numerator;
        CInt denominator;
    public:
        CRational(int n=0, int d=1): numerator(CInt(n)), denominator(CInt(d)) {
            std::cout << "Constructor for " << n << '/' << d << std::endl;
        }
        ~CRational() {
            std::cout << "Destructor for " << numerator.value << '/'
                << denominator.value << std::endl;
        }
    };

    int main() {
        CRational a(1, 2);
        CRational b(3, 4);
        return 0;
    }


  6. (10%) Consider the following program.  Please note that the line number on the left is only shown for your convenience.  They are not part of the code.

      1 #include <iostream>
      2
      3 int main()
      4 {
      5     int total = 0;
      6     int i = 1;
      7     while (i <= 100) {
      8         total += i;
      9         ++i;
     10     }
     11     std::cout << total << std::endl;
     12     return 0;
     13 }

    If we compile this program with "g++ -g q6.cpp -o q6.exe", and run "gdb q6.exe" with the following commands, what value of i shall we obtain?
    break 9 if total >= 3003
    run
    print i

  7. (10%) Determine whether the following code has syntax errors or not.  If it is correct, predict its output.  If it is incorrect, point out the line(s) with syntax mistake(s).

    // Vector
    #include <iostream>
    #include <vector>

    int main()
    {
        std::vector<int> b(2, 5);
        b.resize(4, 9);
        b.insert(b.begin()+1, 3);
        b.erase(b.begin()+3);
        for (size_t i=0; i<b.size(); ++i)
            std::cout << b.at(i) << ' ';
        std::cout << std::endl;
        return 0;
    }

  8. (10%) Suppose you successfully compile the following program by "g++ -I ~solomon/CPP q8.cpp".  Predict the output when you run this program.

    // JSON
    #include <iostream>
    #include <json.hpp>
    using nlohmann::json;
    int main()
    {
       json ex8 = json::parse("[ [1,2,3,4], [5,6,7,8] ]");
       std::cout << ex8.size() << std::endl;
       std::cout << ex8[1].size() << std::endl;
       return 0;
    }


  9. (10%) Determine whether the following code has syntax errors or not.  If it is correct, predict its output.  If it is incorrect, point out the line(s) with syntax mistake(s).
    // Overloading the Decrement Operator
    #include <iostream>
    using std::ostream;

    class CRational {
    friend ostream& operator<<(ostream& o, const CRational& b);
    public:
        CRational(int n = 0, int d = 1): m_numerator(n), m_denominator(d) {}
        CRational& operator--() { m_numerator--; return *this; }
        CRational operator--(int n) { CRational t = *this; m_denominator--; return t; }
    private:
        int m_numerator;
        int m_denominator;
    };

    ostream& operator<<(ostream& o, const CRational& b) {
        o << b.m_numerator << '/' << b.m_denominator;
        return o;
    }

    int main() {
        CRational a(2, 3);
        CRational b(3, 5);
        std::cout << --a << ' ' << b-- << std::endl;
        return 0;
    }

  10. (10%) Consider the following OnDraw() function, what result will be shown on the screen after you run the program?  Please specify the coordinates of endpoints of each line segment.

    // Polygon
    void CQ10View::OnDraw(CDC* pDC)
    {
        int x0 = 100;
        int y0 = 100;
        for (int i = 1; i <= 3; ++i) {
            CPoint p[3] = { CPoint(x0, y0 - 10 * i), CPoint(x0 - 10 * i, y0 + 10 * i), CPoint(x0 + 10 * i, y0 + 10 * i) };
            pDC->Polygon(p, 3);
        }
    }