1.检查错误。

代码：

#include <iostream>

using namespace std;

class Time
{
private:
    /* data */
public:
    Time(/* args */);
    ~Time();
    void set_time(void);
    void show_time(void);
    int hour;
    int minute;
    int sec;
};

Time::Time(/* args */)
{
}

Time::~Time()
{
}

Time t;

int main() {

    t.set_time();//成员函数，需要通过对象来调用
    t.show_time();
    return 0;
}

void Time::set_time(void) {//成员函数，定义的时候需要添加类名来说明
    cin >>t.hour;
    cin >>t.minute;
    cin >>t.sec;
}

void Time::show_time(void) {
    cout <<t.hour <<":" <<t.minute <<":" <<t.sec <<endl;
}

输出结果：

2.成员函数的私有化，定义成员函数。

代码：

 

#include <iostream>

using namespace std;

class Time
{
private:
    int hour;
    int minute;
    int sec;
public:
    Time(/* args */);
    ~Time();

    void set_time(void) {
        cin >>hour;
        cin >>minute;
        cin >>sec;
    }

    void show_time(void) {
        cout <<hour <<":" <<minute <<":" <<sec <<endl;
    }
};

Time::Time(/* args */)
{
}

Time::~Time()
{
}

Time t;

int main() {

    t.set_time();
    t.show_time();
    return 0;
}

输出结果：

3.类内声明，类外实现成员函数。

代码：

9_3.cpp

#include "Student.h"

int main() {
    Student stu;
    stu.set_value();
    stu.display();
    return 0;
}

student.cpp

#include <string>
#include <iostream>

using namespace std;
class Student
{
private:
    int num;
    string name;
    char sex;
public:
    void display();
    void set_value();

};


inline void Student::display() {
    cout << "num = " << num << endl;
    cout << "name = " << name << endl;
    cout << "sex = " << sex << endl; 
}

void Student::set_value() {
    cin >> num;
    cin >> name;
    cin >> sex;
}

输出结果：

4成员函数的声明和实现分离

代码：

9_4.cpp

#include "Student.h"

int main() {
    Student stu;
    stu.set_value();
    stu.display();
    hello();
    return 0;
}

Student.cpp

#include "Student.h"//<>is not fit

void Student::display() {
    cout << "num = " << num << endl;
    cout << "name = " << name << endl;
    cout << "sex = " << sex << endl; 
}

void Student::set_value() {
    cin >> num;
    cin >> name;
    cin >> sex;
}

void hello() {
    cout <<"Hello world1" <<endl;
}

Student.h

#include <string>
#include <iostream>

using namespace std;
class Student
{
private:
    int num;
    string name;
    char sex;
public:
    void display();
    void set_value();

};

输出结果：

6.计算长方体体积

代码：

#include <iostream>

using namespace std;

class Cube
{
private:
    int length;
    int width;
    int height;
public:
    Cube(int l, int w, int h);
    ~Cube();

    int volume();
};

Cube::Cube(int l, int w, int h)
{
    length = l;
    width = w;
    height = h;
}

Cube::~Cube()
{
}

int main() {
    int a,b,c;
    cin >> a >> b >> c;
    Cube c1(a, b, c);
    cout << "volume = " <<c1.volume() <<endl;

    cin >> a >> b >> c;
    Cube c2(a, b, c);
    cout << "volume = " <<c2.volume() <<endl;

    cin >> a >> b >> c;
    Cube c3(a, b, c);
    cout << "volume = " <<c3.volume() <<endl;
    
}

int Cube::volume() {
    return height*width*length;
}

输出结果：