面向对象程序设计——C++
编程专栏
C++风格简单题
百钱问题（1元兑换成1,2,5,分的种类）
#include <iostream>
using namespace std;
int main()
{
int i, j, sum = 0;
for (i = 0; i <= 20; i++)
{
for (j = 0; j <= 50; j++)
{
if (100 - 5 * i - 2 * j >= 0) {
sum++;
cout << "1分：" << (100 - 5 * i - 2 * j) << "\t2分：";
cout << j << "\t5分：" << i << endl;
}
}
}
cout << "sum is "<< sum << endl;
return 0;
}
引用的例子——排序(从小到大)
#include<iostream>
using namespace std;
int main()
{
void change(int &, int &);
int a, b;
cin >> a >> b;
if (a > b) change(a, b);
cout << a <<" "<< b << endl;
return 0;
}
void change(int &a1, int &b1)
{
int t;
t = a1;
a1 = b1;
b1 = t;
}
类和对象题
简单的成员函数题
用类外定义类内成员函数，实现年月日显示。
#include<iostream>
using namespace std;
class Date {
public :
void print();
void setday(int d);
void setmonth(int m);
void setyear(int y);
private:
int day, month, year;
};
void Date::print()
{
cout << "日期为" << year << "年";
cout << month << "月" << day<<"日"<< endl;
}
void Date::setday(int d)
{
day = d;
}
void Date::setmonth(int m) {
month = m;
}
void Date::setyear(int y)
{
year = y;
}
int main()
{
Date thisday;
thisday.setday(3);
thisday.setmonth(6);
thisday.setyear(2021);
thisday.print();
return 0;
}
对象数组题
构建一个类book,其中含有两个私有数据成员qu和price，将qu初始化为1~5，将price初始化为qu的10倍，建立一个有5个元素的数组元素，显示每个对象数组元素的qu*price值。
#include <iostream>
using namespace std;
class book {
private:
int qu, price;
public:
book(int a, int b) {
qu = a;
price = b;
}
void show_money()
{
cout << qu * price << endl;
}
};
int main()
{
book ob[5] = {
book(1,10),
book(2,20),
book(3,30),
book(4,40),
book(5,50)
};
for (int i = 0; i < 5; i++)
ob[i].show_money() ;
return 0;
}
继承与派生类题
面积题
建立基类area_cl的两个派生类rectangle与iosceles 让每一个派生类都包含一个函数area ()分别用来返回与三角形的面积。用构造函数对height与width进行初始化。
写出主程序，矩形高10.0 宽5.0，三角形宽长6.0 高4.0;
通过基类访问虚函数的方法即运行时的多态分别求面积
#include<iostream>
using namespace std;
class area_c1{
protected:
double height;
double width;
public :
area_c1(double r, double s)
{
area_c1::height = r;
area_c1::width = s;
}
virtual double area() = 0;
};
class rectangle :public area_c1{
public :
rectangle(double r, double s):area_c1(r, s)
{}
double area(){
return height * width;
}
};
class isosceles : public area_c1 {
public :
isosceles (double r, double s) :area_c1(r, s)
{}
double area(){
return height * width/2;
}
};
int main() {
area_c1 *ob;
rectangle ob1(10.0, 5.0);
isosceles ob2(4.0, 6.0);
ob = &ob1;
cout<< "矩形面积" << ob->area() << endl;
ob = &ob2;
cout << "三角形面积" << ob->area() << endl;
}
学生和教师
编写一个学生和教师数据输入和显示数据程序，学生数据有编号，姓名，班号，成绩，教师有编号，姓名，职称，和部门。要求将编号，姓名输入和显示设计成一个类person ，并作为学生数据操作类 student 和教师数据操作类teacher的基类。
#include <iostream>
using namespace std;
class person {
private:
int no;
char name[10];
public :
void shuru()
{
cout << "编号"; cin >> no;
cout << "姓名"; cin >> name;
}
void print()
{
cout << "编号" << no << endl;
cout << "姓名" << name << endl;
}
};
class student : public person {
private:
int banhao;
int score;
public:
void shuru()
{
person::shuru();
cout << "班号"; cin >> banhao;
cout << "分数"; cin >> score;
}
void print()
{
person::print();
cout << "班号" << banhao << endl;
cout << "分数" << score <<endl;
}
};
class teacher :public person {
private:
char zhicheng[10];
char apart[10];
public :
void shuru() {
person::shuru();
cout << "职称"; cin >> zhicheng;
cout << "部门"; cin >> apart;
}
void print()
{
person::print();
cout << "职称" << zhicheng<< endl;
cout << "部门" << apart << endl;
}
};
int main()
{
student s1;
teacher t1;
cout << "输入学生数据" << endl;
s1.shuru();
cout << "\n输入老师数据" << endl;
t1.shuru();
cout << "\n显示学生数据" << endl;
s1.print();
cout << "\n显示老师数据" << endl;
t1.print();
return 0;
}
虚函数题
写一个程序，定义抽象基类Container，由它派生出三个派生类：Spere(球体)，Cylinder（圆柱体），Cude (正方体)，用虚函数分别计算几种图形的表面积和体积。
#include <iostream>
using namespace std;
class Container {
protected :
double radiux;
double height;
public :
Container(double ra) {
Container::radiux = ra;
}
double print_ra() {
return radiux;
}
double print_he() {
return height;
}
virtual double s_area() = 0;
virtual double volume() = 0;
};
class sphere :public Container{
public:
sphere(double ra) : Container(ra)
{ }
double s_area()
{
return 4 * 3.14*radiux* radiux;
}
double volume()
{
return 3.14*radiux* radiux*radiux*4/3;
}
};
class cylinder :public Container {
public:
cylinder(double ra,double he) : Container(ra)
{
height = he;
}
double s_area()
{
return 2 * 3.14*radiux* (radiux+height);
}
double volume()
{
return 3.14*radiux* radiux*height;
}
};
class cube :public Container {
public:
cube(double ra) : Container(ra)
{ }
double s_area()
{
return 6*radiux* radiux;
}
double volume()
{
return radiux* radiux*radiux;
}
};
int main()
{
Container *ptr;
sphere obj1(8);
cylinder obj2(3,5);
cube obj3(5);
ptr = &obj1;
cout << "球的半径为" << ptr->print_ra ()<< endl;
cout << "球的表面积为" << ptr->s_area ()<< endl;
cout << "球的体积为" << ptr->volume ()<< endl;
ptr = &obj2;
cout << "圆柱的半径为" << ptr->print_ra() << endl;
cout << "圆柱的高为" << ptr->print_he ()<< endl;
cout << "圆柱的表面积为" << ptr->s_area() << endl;
cout << "圆柱的体积为" << ptr->volume() << endl;
ptr = &obj3;
cout << "正方体的半径为" << ptr->print_ra() << endl;
cout << "正方体的表面积为" << ptr->s_area() << endl;
cout << "正方体的体积为" << ptr->volume() << endl;
return 0;
}