3.5
例子3.1p70
//;使用构造函数修改例子2.3
#include<iostream>
using namespace std;
class Time
{
public:
Time() {
hour = 0;
minute = 0;
sec = 0;
}
void setTime();
void showTime();
private:
int hour;
int minute;
int sec;
};
void Time::setTime()
{
cin >> hour >> minute >> sec;
}
void Time::showTime()
{
cout << hour << ":" << minute << ":" << sec << endl;
}
int main()
{
Time t1;
t1.setTime();
t1.showTime();
Time t2;
t2.showTime();
return 0;
}
例子3.2p72
//两个长方体,已知各自参数,求体积
#include<iostream>
using namespace std;
class Box
{
public:
Box(int, int, int);
int volume();
private:
int height;
int width;
int length;
};
Box::Box(int h, int w, int len)
{
height = h;
width = w;
length = len;
}
int Box::volume()
{
return(height*width*length);
}
int main() {
Box box(12, 25, 30);
cout << "The volume of box is " << box.volume() << endl;
Box box2(15, 30, 21);
cout << "The volume of box2 is " << box2.volume() << endl;
return 0;
}
例子3.3p74
//;在例子3.2基础上,构建两个一个无参数,一个有参数
#include<iostream>
using namespace std;
class Box
{
public:
Box();
Box(int h, int w, int len) :height(h), width(w), length(len) {}
int volume();
private:
int height;
int width;
int length;
};
Box::Box()
{
height = 10;
width = 10;
length = 10;
}
int Box::volume()
{
return(height*width*length);
}
int main()
{
Box box1;
cout << "The volume of box1 is " << box1.volume() << endl;
Box box2(15,30,25);
cout << "The volume of box2 is " << box2.volume() << endl;
return 0;
}
例子3.4p
//在例子3.3基础上,构造函数改用含默认参数的,且全为10
#include<iostream>
using namespace std;
class Box
{
public:
Box(int h = 10, int w = 10, int len = 10);
int volume();
private:
int height;
int width;
int length;
};
Box::Box(int h, int w, int len)
{
height = h;
width = w;
length = len;
}
int Box::volume()
{
return (height*width*length);
}
int main()
{
Box box1;
cout << "The volume of box1 is " << box1.volume() << endl;
Box box2(15);
cout << "The volume of box2 is " << box2.volume() << endl;
Box box3(15, 30);
cout << "The volume of box3 is " << box3.volume() << endl;
Box box4(15, 30, 20);
cout << "The volume of box4 is " << box4.volume() << endl;
return 0;
}
例子3.5p79
//;包含析构函数和构造函数//有问题
#include<string>
#include<iostream>
using namespace std;
class Student
{
public:
Student(int n, string nam, char s)
{
num = n;
name = nam;
sex = s;
cout << "Constructor called" << endl;
}
~Student()
{
cout << "Destructor called" << endl;
}
void display()
{
cout << "num:" << num << endl;
cout << "name:" << name << endl;
cout << "sex:" << sex << endl << endl;
}
private:
int num;
string name[20];
char sex;
};
int main()
{
Student stu1(10010, "Wang_li", 'f');
stu1.display();
Student stu2(10011, "Zhang_fan", 'm');
stu2.display();
return 0;
}
例子3.6p
//对象数组:计算和输出3个立方体的体积//书上的错误的修改过来了
#include<iostream>
using namespace std;
class Box
{
public:
Box(int h = 10, int w = 12, int len = 15) :height(h), width(w), length(len) {}
int volume();
private :
int height;
int width;
int length;
};
int Box::volume()
{
return (height*width*length);
}
int main()
{
Box a[3] = {
Box(10,12,15),
Box(15,18,20),
Box(16,20,26)
//return 0;
};
cout << "volume of a[0] is " << a[0].volume() << endl;
cout << "volume of a[1] is " << a[1].volume() << endl;
cout << "volume of a[2] is " << a[2].volume() << endl;
}
例子3.7p87
这里很重要,要细心理解
//适用对象指针输出时分秒//这里很重要,要细心理解
#include<iostream>
using namespace std;
class Time
{
public:
Time(int, int, int);
int hour;
int minute;
int sec;
void getTime();
private:
};
Time::Time(int h, int m, int s)
{
hour = h;
minute = m;
sec = s;
}
void Time::getTime() {
cout << hour << ":" << minute << ":" << sec << endl;
}
int main()
{
Time t1(10, 13, 56);
int *p1 = &t1.hour;//为何这里有&
cout << *p1 << endl;
t1.getTime();
Time *p2 = &t1;
p2->getTime();
void(Time:: *p3)();
p3 = &Time::getTime;//为什么加了()之后就报错呢
(t1.*p3)();
return 0;
}
例子3.8p97
//使用对象的引用,输出时分秒//可以通过类外函数(参数必须为引用,否则无效),修改相关参数
#include<iostream>
using namespace std;
class Time {
public:
Time(int, int, int);
int hour;
int minute;
int sec;
};
Time::Time(int h, int m, int s)
{
hour = h;
minute = m;
sec = s;
}
void fun(Time &t)//&必须要有,否则无效
{
t.hour = 18;
//t.minute = 30;
}
int main()
{
Time t1(10, 13, 56);//此时里面参数10,已经被该对象的引用给覆盖了
fun(t1);
cout << t1.hour<<":"<<t1.minute<<":"<<t1.sec << endl;
return 0;
}
例子3.9p100
//对象赋值给另外个对象(必须同个类才行)
#include<iostream>
using namespace std;
class Box
{
public:
Box(int = 10, int = 10, int = 10);//这里居然不用写出变量名
int volume();
private:
int height;
int width;
int length;
};
Box::Box(int h, int w, int len)
{
height = h;
width = w;
length = len;
}
int Box::volume()
{
return (height*width*length);
}
int main()
{
Box box1(15, 30, 25), box2;//即使没有括号()里面,也能运行
cout << "The volume of box1 is " << box1.volume() << endl;
box2 = box1;
cout << "The volume of box2 is " << box2.volume() << endl;
}
例子3.10p105
//使用静态数据成员输出立方体的体积
#include<iostream>
using namespace std;
class Box
{
public:
Box(int, int);
int volume();
static int height;
int width;
int length;
};
Box::Box(int w, int len)
{
width = w;
length = len;
}
int Box::volume()
{
return (height*width*length);
}
int Box::height = 10;
int main()
{
Box box1(15, 20), box2(20, 30);
cout << box1.height << endl;
cout << box2.height << endl;
cout << Box::height << endl;
cout << box1.volume()<< endl;
return 0;
}
例子3.11p107
//使用静态成员函数统计学生平均成绩//没有通过编译
#include<iostream>
using namespace std;
class Student
{
public:
Student(int n,int a,float s):num(n),age(a),score(s){}
void total();
static float average();
private:
int num;
int age;
float score;
static float sum;
static int count;
};
void Student::total()
{
sum += score;
count++;
}
float Student::average()
{
return(sum / count);
}
int main()
{
Student stu[3] =
{
Student(1001,18,70),
Student(1002,18,78),
Student(1005,20,98)
};//这里必须添加;因为这是数组
int n;
cout << "please input the number of students: ";
cin >> n;
for (int i = 0; i < n; i++)
stu[i].total();
cout<< "the average score of " << n << "students is " << Student::average() << endl;
return 0;
}
例子3.12p10
