C_C++程序设计与上机指导

【例11.1】 #include "iostream.h" #include "iomanip.h" void main() { int a,b; cout<<"Input two numbers:\n"; cin>>a>>b; cout<<"a="<<a<<setw(5)<<"b="<<b<<endl; cout<<"The max is:"<<(a>b?a:b)<<endl; } 【例11.3】 #include "iostream.h" void main() { int a=5; cout<<"a="<<a<<endl; int &b=a; b+=10; int *p=&b; cout<<"b="<<b<<endl; cout<<"a="<<a<<endl; cout<<"*p="<<*p<<endl; } 【例11.3】 #include "iostream.h" #include "iomanip.h" void swap(int &a,int &b) { int temp; temp=a; a=b; b=temp; } void main( ) { int i=3,j=5; cout<<"i="<<i<<setw(5)<<"j="<<j<<endl; swap (i,j); cout<<"i="<<i<<setw(5)<<"j="<<j<<endl; } 【例11.4】 #include "iostream.h" int a=10; void main() { int a=5; cout<<"a="<<a<<endl; //输出局部变量a cout<<"a="<<::a<<endl; //输出全局变量a } 【例11.5】 #include “iostream.h” inline double circlearea(double radius) //内联函数定义，计算圆的面积 { return 3.14*radius*radius; } void main() { double r,area; cout<<”Enter the radius:”; cin>>r; area=circlearea(r); //编译时此处用函数cirlearea的函数体替换 cout<<”The area is:”<<area<<endl; } 【例11.6】 #include "iostream.h" void main() { int add(int,int); long add(long,long); double add(double,double); int add(int,int,int); int a,b,c; long x,y; double m,n; cout<<"Input int numbers:"; cin>>a>>b>>c; cout<<"Input long numbers:"; cin>>x>>y; cout<<"Input double numbers:"; cin>>m>>n; cout<<"Sum of two int:"<<add(a,b)<<endl; cout<<"Sum of three int:"<<add(a,b,c)<<endl; cout<<"Sum of long:"<<add(x,y)<<endl; cout<<"Sum of double:"<<add(m,n)<<endl; } int add(int i,int j) { return i+j; } int add(int i,int j,int k) { return i+j+k; } long add(long i,long j) { return i+j; } double add(double i,double j) { return i+j; } 【例11.7】 #include "iostream.h" int add(int m=10,int n=20) { return m+n; } void main() { cout<<add(5,10)<<endl; cout<<add(5)<<endl; cout<<add()<<endl; } 【例11.8】 #include "iostream.h" #include "iomanip.h" struct student{ char NO[4]; char name[10]; int age; }; void main() { student *p; p=new student; cin>>p->NO>>p->name>>p->age; cout<<"NO:"<<p->NO<<endl<<"name:"<<p->name<<endl<<"age:"<<p->age<<endl; delete p; } 【例11.9】 #include "iostream.h" const double PI=3.14159; //常量定义 class circle { private: double r; public: void set(double); double area(); }cir,*pcir; void circle::set(double value) //为私有数据成员赋值 { r=value; } double circle::area() //计算面积 { return r*r*PI; } void main() { cir.set(3.5); pcir=new circle; pcir->set(3.5); cout<<"area="<<cir.area()<<endl; cout<<"parea="<<pcir->area()<<endl; delete pcir; } 【例11.10】 #include "iostream.h" #include "string.h" class student { private: char NO[4]; char name[10]; int age; public: student(char ch1[4],char ch2[10],int m); //构造函数 void disp( ); ~student(); //析构函数 }; student::student(char ch1[4],char ch2[10],int m) //构造函数定义 { cout<<"constructor called!"<<endl; strcpy(NO,ch1); strcpy(name,ch2); age=m; } student::~student() //析构函数定义 { cout<<"disconstructor called!"<<endl; } void student::disp() { cout<<"NO:"<<NO<<endl; cout<<"name:"<<name<<endl; cout<<"age:"<<age<<endl; } void main() { student stu1("001","zhangming",20),stu2(“002”,”liyi”,21); stu.disp(); } 【例11.11】 #include "iostream.h" class A { public: A(int i) { a=i; cout<<"A:constructor called"<<endl; }; ~A() { cout<<"A:destructor called"<<endl; } void print() const { cout<<a<<endl; } private: int a; }; class B:public A { public: B(int i,int j); ~B(); void print() const; private: int b; }; B::B(int i,int j):A(i) { b=j; cout<<"B:constructor called"<<endl; } B::~B() { cout<<"B:destructor called"<<endl; } void B::print() const { A::print(); cout<<b<<endl; } void main() { B obj(5,6); obj.print(); } 【例11.12】 #include "iostream.h" class complex { public: complex(double r=0.0,double i=0.0) //构造函数 { real=r; imag=i; } complex operator +(complex c2); //＋重载为成员函数 complex operator -(complex c2); //－重载为成员函数 void display(); private: double real,imag; }; complex complex::operator+(complex c2) { complex c; c.real=c2.real+real; c.imag=c2.imag+imag; return complex(c.real,c.imag); } complex complex::operator-(complex c2) { complex c; c.real=real-c2.real; c.imag=imag-c2.imag; return complex(c.real,c.imag); } void complex::display() { if(imag>0) cout<<real<<"+"<<imag<<"i"<<endl; else cout<<real<<imag<<"i"<<endl; } void main() { complex c1(7,5),c2(1,20),c3; cout<<"c1="; c1.display(); cout<<"c2="; c2.display(); c3=c1+c2; cout<<"c3=c1+c2="; c3.display(); c3=c1-c2; cout<<"c3=c1-c2="; c3.display(); } 【例11.13】 #include "iostream.h" class instrument { public: void play( ) const { cout<<"instrument::play"<<endl; } }; class wind:public instrument { public: void play( ) const { cout<<"wind::play"<<endl; } }; void tune(instrument &i) { i.play( ); } void main() { wind flute; tune(flute); } 【例11.14】 #include "iostream.h" class instrument { public: virtual void play() const //虚函数 { cout<<"instrument::play"<<endl; } }; class wind:public instrument { public: void play() const //虚函数 { cout<<"wind::play"<<endl; } }; void tune(instrument &i) { i.play(); } void main() { wind obj_w; instrument obj_i; tun