VC++习题 第7~10章 面向对象和类

01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
class Person {
private:
    string name;
    int age;
public:
    void setName(string n) {
        name = n;
    }
    void setAge(int a) {
        age = a;
    }
    string getName() {
        return name;
    }
    int getAge() {
        return age;
    }
}; 

01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
Person p; 
p.setName("Tom"); 
cout << p.getName() << endl;
访问私有成员需要通过公有成员函数来访问，例如：
class Person{
private:
string name;
public:
void setName(string n){
name = n;
}
string getName(){
return name;
}
void printName(){
cout<<name<<endl;
}
};
Person p;
p.setName("Tom");
p.printName();

01
02
03
04
Person &Person::setName(string n){
this->name = n;
return *this;
}

01
02
03
void Person::printName(){
cout << this->name <<endl;
}

01
02
Person p;
p.setName(Tom).setAge(20);

01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
#include <iostream>
#include <string>

using namespace std;

class Student {
private:
    string name;
    string id;
    float english;
    float math;
    float computer;

public:
    // 设置姓名和学号
    void setName(string name) {
        this->name = name;
    }
    void setId(string id) {
        this->id = id;
    }

    // 设置三门课成绩
    void setScores(float english, float math, float computer) {
        this->english = english;
        this->math = math;
        this->computer = computer;
    }

    // 求平均成绩
    float getAverage() {
        return (english + math + computer) / 3;
    }

    // 输出数据
    void print() {
        cout << "Name: " << name << endl;
        cout << "ID: " << id << endl;
        cout << "English: " << english << endl;
        cout << "Math: " << math << endl;
        cout << "Computer: " << computer << endl;
        cout << "Average score: " << getAverage() << endl;
    }
};

int main() {
    Student s;
    s.setName("Tom");
    s.setId("1001");
    s.setScores(89.5, 93.2, 87.8);
    s.print();

    return 0;
}

01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
#include<iostream>
using namespace std;

class CDate {
private:
    int year;
    int month;
    int day;

public:
    // 构造函数，初始化日期
    CDate(int y=0, int m=0, int d=0) {
        year = y;
        month = m;
        day = d;
    }

    // 成员函数，设置日期
    void setDate(int y, int m, int d) {
        year = y;
        month = m;
        day = d;
    }

    // 成员函数，用格式“月/日/年”输出日期
    void printDate() {
        cout << month << "/" << day << "/" << year << endl;
    }

    // 成员函数，对当前日期加一天
    void nextDay() {
        int daysInMonth;

        // 判断当前月份天数
        switch (month) {
            case 2:
                // 如果当前是闰年，二月有29天
                if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0)
                    daysInMonth = 29;
                // 否则二月有28天
                else
                    daysInMonth = 28;
                break;

            case 4:
            case 6:
            case 9:
            case 11:
                daysInMonth = 30;
                break;

            default:
                daysInMonth = 31;
        }

        // 如果当前天数等于当月天数，进位
        if (day == daysInMonth) {
            day = 1;

            // 如果当前月份等于12，进位到下一年
            if (month == 12) {
                month = 1;
                year++;
            } else {
                month++;
            }
        } else {
            day++;
        }
    }
};

int main() {
    CDate date(2021, 3, 31);    // 初始化日期为2021年3月31日
    date.printDate();           // 输出日期
    date.nextDay();             // 将日期加一天
    date.printDate();           // 输出加一天后的日期

    return 0;
}

01
02
03
04
05
06
07
class Person {
public:
    Person(int age, const std::string& name) : m_age(age), m_name(name) {}
private:
    int m_age;
    std::string m_name;
};

01
02
03
04
05
06
07
08
09
10
class Person {
public:
    friend void printAge(const Person& p);
private:
    int m_age;
};

void printAge(const Person& p) {
    std::cout << p.m_age << std::endl;
}

01
02
03
04
05
06
07
08
class Person {
public:
    static int getCount() { return s_count; }
private:
    static int s_count;
};

int Person::s_count = 0;

01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
#include <iostream>
#include <cmath>
using namespace std;
// 计算整型数的两点间距离
double distance(int x1, int y1, int x2, int y2) {
    return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
}
// 计算实型数的两点间距离
double distance(double x1, double y1, double x2, double y2) {
    return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
}
int main() {
    int x1 = 1, y1 = 2, x2 = 3, y2 = 4;
    double dx1 = 1.0, dy1 = 2.0, dx2 = 3.0, dy2 = 4.0;

    // 调用整型数版本的distance函数
    cout << "The distance between two points (int version): " << distance(x1, y1, x2, y2) << endl;

    // 调用实型数版本的distance函数
    cout << "The distance between two points (double version): " << distance(dx1, dy1, dx2, dy2) << endl;

    return 0;
}

01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
#include <iostream>
#include <cmath>

using namespace std;

class Cpoint {
private:
    double x, y;
public:
    Cpoint(double _x = 0.0, double _y = 0.0) : x(_x), y(_y) {}
    double distance(const Cpoint &p) const {
        return sqrt(pow(x - p.x, 2) + pow(y - p.y, 2));
    }
    int distance(const Cpoint &p) const {
        return static_cast<int>(round(sqrt(pow(x - p.x, 2) + pow(y - p.y, 2))));
    }
};

int main() {
    Cpoint p1(0.0, 0.0), p2(3.0, 4.0);
    cout << "distance between p1 and p2 is " << p1.distance(p2) << endl;
    cout << "distance between p1 and p2 is " << p1.distance(p2) << endl;
    return 0;
}

01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
#include <iostream>
#include <cmath>
using namespace std;

class Square {
public:
    int square(int x) {
        return x * x;
    }
    
    double square(double x) {
        return x * x;
    }
    
    double square(long double x) {
        return x * x;
    }
};

int main() {
    Square s;
    int a = 5;
    double b = 2.5;
    long double c = 1.234567890123456789;

    cout << "The square of " << a << " is " << s.square(a) << endl;
    cout << "The square of " << b << " is " << s.square(b) << endl;
    cout << "The square of " << c << " is " << s.square(c) << endl;

    return 0;
}

01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
#include <iostream>
using namespace std;

class Complex {
private:
    double real, imag; //实部和虚部
public:
    //构造函数
    Complex(double r = 0, double i = 0) : real(r), imag(i) {}

    //输出函数
    void print() const {
        cout << "(" << real << ", " << imag << ")" << endl;
    }
};

01
02
03
04
05
06
int main() {
    Complex c(3.2, 1.5); //创建一个复数对象
    c.print(); //输出复数值

    return 0;
}

01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
#include <iostream>
using namespace std;

class Factorial {
public:
    int compute(int n) {
        if (n == 0) {
            return 1;
        } else {
            return n * compute(n - 1);
        }
    }
};

int main() {
    Factorial f;
    int n = 8;
    int result = f.compute(n);
    cout << n << "的阶乘是：" << result << endl;
    return 0;
}

01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
#include <string>
using namespace std;

class DecimalToHex {
private:
    int decimal;
    string hex;

public:
    DecimalToHex(int d) : decimal(d) {}

    void convert() {
        string hex_digits = "0123456789ABCDEF";
        int quotient = decimal;

        while (quotient > 0) {
            int remainder = quotient % 16;
            hex = hex_digits[remainder] + hex;
            quotient /= 16;
        }
    }

    void print() {
        cout << hex << endl;
    }
};

01
02
03
04
05
06
07
08
09
10
#include <iostream>
using namespace std;

int main() {
    DecimalToHex dth(4567);
    dth.convert();
    dth.print();

    return 0;
}

01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
#include <iostream>

class GCD_LCM {
public:
    GCD_LCM(int a, int b) : num1(a), num2(b) {}

    int gcd() {  // 求最大公约数
        int a = num1, b = num2;
        while (b != 0) {
            int temp = a % b;
            a = b;
            b = temp;
        }
        return a;
    }

    int lcm() {  // 求最小公倍数
        return num1 * num2 / gcd();
    }

private:
    int num1, num2;
};

int main() {
    int a, b;
    std::cout << "Please enter two integers: ";
    std::cin >> a >> b;

    GCD_LCM obj(a, b);

    std::cout << "The GCD of " << a << " and " << b << " is " << obj.gcd() << std::endl;
    std::cout << "The LCM of " << a << " and " << b << " is " << obj.lcm() << std::endl;

    return 0;
}

01
02
03
04
void main(){
	Test t(88,32);
	t.print();
}

01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
#include <iostream>
using namespace std;
class Test {
private:
    int a, b;
public:
    Test(int x, int y) {  // 构造函数
        a = x;
        b = y;
        cout << "调用了构造函数" << endl;
    }
    ~Test() {  // 析构函数
        cout << "调用了析构函数" << endl;
    }
    void print() {  // 输出相减结果
        cout << a << " - " << b << " = " << a-b << endl;
    }
};
int main() {
    Test t(88, 32);
    t.print();
    return 0;
}

01
02
03
调用了构造函数
88 - 32 = 56
调用了析构函数

01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
#include <iostream>
#include <cmath>

using namespace std;

class Cpoint {
public:
    Cpoint(double x = 0, double y = 0) : m_x(x), m_y(y) {
        cout << "Cpoint constructor called." << endl;
    }
    ~Cpoint() {
        cout << "Cpoint destructor called." << endl;
    }
    double getX() const {
        return m_x;
    }
    double getY() const {
        return m_y;
    }
private:
    double m_x;
    double m_y;
};

class tria {
public:
    tria(const Cpoint& p1, const Cpoint& p2, const Cpoint& p3) : m_p1(p1), m_p2(p2), m_p3(p3) {
        cout << "tria constructor called." << endl;
    }
    ~tria() {
        cout << "tria destructor called." << endl;
    }
    double area() const {
        double a = sqrt(pow(m_p2.getX() - m_p1.getX(), 2) + pow(m_p2.getY() - m_p1.getY(), 2));
        double b = sqrt(pow(m_p3.getX() - m_p2.getX(), 2) + pow(m_p3.getY() - m_p2.getY(), 2));
        double c = sqrt(pow(m_p1.getX() - m_p3.getX(), 2) + pow(m_p1.getY() - m_p3.getY(), 2));
        double s = (a + b + c) / 2.0;
        return sqrt(s * (s - a) * (s - b) * (s - c));
    }
private:
    Cpoint m_p1;
    Cpoint m_p2;
    Cpoint m_p3;
};

int main() {
    Cpoint p1(0, 0);
    Cpoint p2(3, 0);
    Cpoint p3(0, 4);
    tria t(p1, p2, p3);
    cout << "The area of the triangle is: " << t.area() << endl;
    return 0;
}

01
02
03
04
05
06
07
08
09
Cpoint constructor called.
Cpoint constructor called.
Cpoint constructor called.
tria constructor called.
The area of the triangle is: 6
tria destructor called.
Cpoint destructor called.
Cpoint destructor called.
Cpoint destructor called.

01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
#include <iostream>
#include <cmath>
using namespace std;

class CPoint; // 前置声明

class CTria {
private:
    CPoint p1, p2, p3;
public:
    CTria(CPoint a, CPoint b, CPoint c): p1(a), p2(b), p3(c) {}
    friend double getArea(CTria t); // 声明友元函数
};

class CPoint {
private:
    double x, y;
public:
    CPoint(double a = 0, double b = 0): x(a), y(b) {}
    friend double getDistance(CPoint a, CPoint b);
    friend double getArea(CTria t);
};

double getDistance(CPoint a, CPoint b) {
    return sqrt((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y));
}

double getArea(CTria t) {
    double a = getDistance(t.p1, t.p2);
    double b = getDistance(t.p2, t.p3);
    double c = getDistance(t.p3, t.p1);
    double p = (a + b + c) / 2;
    return sqrt(p * (p - a) * (p - b) * (p - c));
}

int main() {
    CPoint p1(0, 0), p2(3, 0), p3(0, 4);
    CTria t(p1, p2, p3);
    cout << "三角形的面积为：" << getArea(t) << endl;
    return 0;
}

01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
#include <iostream>
using namespace std;

class Football {
public:
    Football(int s) : score(s) {
        totals += score;
        count++;
        cout << "Add a score: " << score << endl;
    }

    static int re_totals() {
        return totals;
    }

    static int re_count() {
        return count;
    }

private:
    int score;
    static int totals;
    static int count;
};

int Football::totals = 0;
int Football::count = 0;

int main() {
    Football f1(2);
    Football f2(3);
    Football f3(1);

    cout << "The total scores: " << Football::re_totals() << endl;
    cout << "The number of scores: " << Football::re_count() << endl;

    return 0;
}

01
02
03
04
05
Add a score: 2
Add a score: 3
Add a score: 1
The total scores: 6
The number of scores: 3