C++若干程序.doc

WIN32控制台的若干程序：1. 源文件中：这个例子着重注意枚举类型的联合类型的应用。枚举和联合都是类的成员变量。#include using namespace std;const float PI=3.1416;#include class datatypeprivate:enumcharacter,interger,float_pointdtype;unionchar c;int i;float f;public:datatype(char cc)c=cc;dtype=character;datatype(int ii)i=ii;dtype=interger;datatype(float ff)f=ff;dtype=float_point;void printf();void datatype:printf()switch (dtype)case character:coutcharacter:cendl;break;case interger:coutinterger:iendl;break;case float_point:coutfloat_point:fendl;break;default:break;void main() datatype A(n),B(5),C(4.55f);A.printf();B.printf();C.printf();2. 这个例子注意友元函数应用和引用应用。为了测试引用成员变量调用，我自己做了一个测试程序，如下：#include using namespace std;void swap(int &x,int &y)int temp;temp=x;x=y;y=temp;void main()int a=10,b=20;couta=ab=bendl;swap(a,b);couta=ab=bendl;由此例可以看出，引用是变量的别名，两个要变一起变。若此例没用引用，即代码为：#include using namespace std;void swap(int x,int y)int temp;temp=x;x=y;y=temp;void main()int a=10,b=20;couta=ab=bendl;swap(a,b);couta=ab=bendl;则结果为：可以看到，交换的功能没有实现。为了测试会发生这样的结果，我们的代码如下：#include using namespace std;void swap(int x,int y)coutx=xy=yendl;int temp;temp=x;x=y;y=temp;coutx=xy=yendl;void main()int a=10,b=20;couta=ab=bendl;swap(a,b);couta=ab=bendl;此时结果如下：由上图可以看到，X 和Y值确实做了交换，但是交换后的参数没有传回来。所以用引用的话，就能保证交换后的参数传回来。#include using namespace std;class boat;class carprivate: int weight;public:car(int j) weight=j;friend int totalweight(car &car1,boat &boat1);class boatprivate: int weight;public: boat(int j)weight=j;friend int totalweight(car &car1,boat &boat1); ;int totalweight(car &car1,boat &boat1)return car1.weight+boat1.weight;void main() car c1(4); boat b1(5); couttotalweight(c1,b1)endl;3. 排序功能：int main()int a10=28,6,99,7,0,34,67,33,25,84,i=0,j=0,temp=0; for (i=0;i10;i+) for (j=i;j10;j+) if (aiaj) temp=ai;ai=aj;aj=temp; for (i=0;i10;i+) coutai的值:ai ; 4,类的构造函数和析构函数调用：#include using namespace std;class Pointpublic:Point();Point(int x,int y);Point();void move(int newx,int newy);int getx() const return x;int gety() const return y;static void showcount();private:int x,y;Point:Point()x=y=0;coutdefault construct calledendl;Point:Point(int x,int y):x(x),y(y) coutconstruct calledendl;Point:Point()coutdeconstruct calledendl;void Point:move(int newx,int newy)coutmoving the point to(newx,newy)endl;x=newx;y=newy;void main()coutentering main.endl;Point a2;for (int i=0;i2;i+) ai.move(i+10,i+20);coutexiting main.endl;结果如下：5,指针操作：#include using namespace std;void main()int *p; 应该为：int *p=new int;错误原因：指针没有初始化，也就是没有指向某个确定的内存单元，它指向内存中的一个随机地址，给这个随机地址赋值时是非常危险的。（也就在在使用指针的时候，必须要初始化。）*p=9;cout*p;代码是错误的。6.关于字符串操作的例子：#include #include using namespace std;class Employeepublic:Employee(char *n,char *s,char *c,char *y)strcpy(name,n);strcpy(shreet,s);strcpy(city,c);strcpy(youbian,y);void change_name(char *newname)strcpy(name,newname);void display()coutname is:nameendl;coutshreet is:shreetendl;coutcity is:cityendl;coutyoubian is:youbianendl;private:char name20;char shreet50;char city20;char youbian10; void main() Employee employe1(李+,金色月亮6幢4单元901,北京市,089231); employe1.change_name(刘+); employe1.display(); 7.类的继承问题：#include using namespace std;class Shapepublic:Shape()Shape()virtual float GetArea()return -1;class Circle: public Shape public:Circle(float radius):itsRadius(radius)Circle()float GetArea()return 3.14*itsRadius*itsRadius;private:float itsRadius;class Rectangle: public Shape public:Rectangle(float len,float width):itsLength(len),itsWidth(width)Rectangle()virtual float GetArea()return itsWidth*itsLength; private:float itsWidth;float itsLength;class Square: public Rectangle public:Square(float len);Square();Square:Square(float len):Rectangle(len,len)int main()Shape *sp;sp=new Circle(5);coutThe area of the Circle is GetArea()endl;delete sp;sp=new Rectangle(4,6);coutThe area of the Rectangle is GetArea()endl;delete sp;sp=new Square(5);coutThe area of the Square is GetArea()endl;delete sp;return 0;7.#include using namespace std;class objectprivate:int Weight;public:object()cout 构造object对象endl;Weight=0;int GetWidth()return Weight;void SetWeight(int n)Weight=n;object()cout析构object对象endl;class box:public objectprivate:int Height,Width;public:box()cout构造box对象 endl;Height=Width=0;int GetHeight()return Height;void SetHeight(int n)Height=n;int GetWidth()return Width;void SetWidth(int n)Width=n;box()cout析构box对象endl;int main()box a;return 0;8.#include using namespace std;class BaseClasspublic:void fn1();void fn2();void BaseClass:fn1()cout调用基类的函数fn1()endl;void BaseClass:fn2()cout调用基类的函数fn2()endl;class DerivedClass:public BaseClasspublic:void fn1();void fn2();void DerivedClass:fn1()cout调用派生类的函数fn1()endl;void DerivedClass:fn2()cout调用派生类的函数fn2()fn1();pBaseClass-fn2();pDerivedClass-fn1();pDerivedClass-fn2();return 0;9.#include #include using namespace std;class Documentpublic:Document();Document(char *name);char *Name;void PrintNameOf();Document:Document(char *name)Name=new charstrlen(name)+1;strcpy(Nam