本文学习自狄泰软件学院 唐佐林老师的 C++深度解析教程，图片全部来源于课程PPT，仅用于个人学习记录

第13课 - 进阶面向对象（上）

类和对象

类和对象是面向对象中的两个基本概念
类：指的是一类事物，是一个抽象的概念
对象：指的是属于某个类的具体实体
类是一种模型，这种模型可以创建出不同的对象实体
对象实体是类模型的一个具体实例

小结

每个类可以有多个对象
每个对象必然属于某个类

第14课 - 进阶面向对象（下）

类之间的基本关系

继承

从已存在类细分出来的类和原类之间具有继承关系（is a）
继承的类（子类）拥有原类（父类）的所有属性和行为
如下图：子类是惠普电脑和苹果电脑；父类是电脑

组合

一些类的存在必须依赖于其他类的关系叫组合
组合的类在某一个局部上由其他的类组成

如下图：

类的表示法

利用继承简化重复的属性和行为

利用结构体、变量和函数描述

实验-类的继承

#include <stdio.h>struct Biology {bool living;
};struct Animal : Biology {bool movable;void findFood() { }
};struct Plant : Biology {bool growable;
};struct Beast : Animal {void sleep() { }
};struct Human : Animal {void sleep() { }void work() { }
};int main()
{return 0;
}

第15课 - 类与封装的概念

实验-定义访问级别

#include <stdio.h>#include <stdio.h>struct Biology 
{bool living;
};struct Animal : Biology 
{bool movable;void findFood(){ }
};struct Plant : Biology 
{bool growable;
};struct Beast : Animal 
{void sleep() { }
};struct Human : Animal 
{void sleep() { printf("I'm sleeping...\n");}void work() { printf("I'm working...\n");}
};struct Girl : Human
{
private:int age;int weight;
public:void print(){age = 22;weight = 48;printf("I'm a girl, I'm %d years old.\n", age);printf("My weight is %d kg.\n", weight);}
};struct Boy : Human
{
private:int height;int salary;
public:int age;int weight;void print(){height = 175;salary = 9000;printf("I'm a boy, my height is %d cm.\n", height);printf("My salary is %d RMB.\n", salary);}    
};int main()
{Girl g;Boy b;// g.age=10;// error: 'int Girl::age' is private within this contextg.print();b.age = 19;b.weight = 120;//b.height = 180;// error: 'int Boy::height' is private within this contextb.print();return 0;
}

cmd

E:\test>g++ 15-1.cppE:\test>a
I'm a girl, I'm 22 years old.
My weight is 48 kg.
I'm a boy, my height is 175 cm.
My salary is 9000 RMB.

实验

#include <stdio.h>int i = 1;struct Test
{
private://私有的，只允许类内部访问int i;public:int j;int getI(){i = 3;return i;}
};int main()
{int i = 2;Test test;test.j = 4;printf("i = %d\n", i);              // i = 2;printf("::i = %d\n", ::i);          // ::i = 1;//printf("test.i = %d\n", test.i);    // Error  error: 'int Test::i' is private within this contextprintf("test.j = %d\n", test.j);    // test.j = 4printf("test.getI() = %d\n", test.getI());  // test.getI() = 3return 0;
}
/*
i = 2
::i = 1
test.j = 4
test.getI() = 3*/

小结

第16课 - 类的真正形态

实验-struct&class

#include <stdio.h>struct A
{// defualt to publicint i;// defualt to publicint getI(){return i;}
};class B
{// defualt to privateint i;// defualt to privateint getI(){return i;}
};int main()
{A a;B b;a.i = 4;printf("a.getI() = %d\n", a.getI());// b.i = 4;//error: 'int B::i' is private within this context//printf("b.getI() = %d\n", b.getI());// error: 'int B::getI()' is private within this contextreturn 0;
}
/*
E:\test>g++ 16-1.cppE:\test>a
a.getI() = 4
*/

实验-operator类的实现

//operator.h
#ifndef _OPERATOR_H_
#define _OPERATOR_H_
class Operator
{
private:char mc;double mp0;double mp1;
public:bool setOperator(char op);void setParameter(double p0,double p1);bool result(double& r);};#endif//operator.c
#include "operator.h"
bool Operator::setOperator(char op){bool ret = false;if( (op == '+') || (op == '-') || (op == '*') || (op == '/') ){ret = true;mc = op;}else{mc = '\0';}return ret;//    bool res=false;
//    operator_cla::mc=mmc;
//    res=true;
//    return res;
}
void Operator::setParameter(double p0,double p1)
{Operator::mp0=p0;Operator::mp1=p1;
}
bool Operator::result(double& r)
{bool res=false;switch(mc){case '+':r=Operator::mp0+Operator::mp1;res=true;break;case '-':r=Operator::mp0-Operator::mp1;res=true;break;case '*':r=Operator::mp0*Operator::mp1;res=true;break;case '/':if(Operator::mp1>-0.000000001&&Operator::mp1<0.000000001){//break;}else{r=Operator::mp0/Operator::mp1;res=true;}break;}return res;}//main.c
#include <stdio.h>
#include "operator.h"int main()
{double r=0;Operator op;op.setOperator('+');op.setParameter(3.5,6);if(op.result(r)){printf("3.5+6=%f\n",r);}op.setOperator('-');op.setParameter(3.5,6);if(op.result(r)){printf("3.5-6=%f\n",r);}op.setOperator('/');op.setParameter(3.5,0);if(op.result(r)){printf("3.5/0=%f\n",r);}else{printf("3.5/0 calculate error\n");}return 0;
}
/*
3.5+6=9.500000
3.5-6=-2.500000
3.5/0 calculate error
*/

小结