这是考试前总结的面向对象程序设计书上的例题，以及特殊函数和自己的分析；这是考试前总结的面向对象程序设计书上的例题，以及特殊函数和自己的分析；这是考试前总结的面向对象程序设计书上的例题，以及特殊函数和自己的分析
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//函数重载 1.6 #include "iostream" using namespace std; int max(int a,int b){ return a>b?a:b; } float max(float a,float b){ return a>b?a:b; } long max(long a,long b){ return a>b?a:b; } int main(){ int a,b; cin>>a>>b; cout<<max(a,b)<<endl; return 0; } //函数模板 1.8 //使用模板时不能只使用两个参数，会报错，如 //[Error] call of overloaded 'max(int&, int&)' is ambiguous #include "iostream" using namespace std; template <typename T> T max(T a,T b,T c){ if(b>a) a=b; if(c>a) a=c; return a; } int main(){ int i1=8,i2 = 5,i3 = 6,i; double d1 = 56.9,d2 = 90.765,d3 = 43.1 ,d; long g1 = 678435,g2 = -1555,g3 = 784354,g; i = max(i1,i2,i3); d = max(d1,d2,d3); g = max(g1,g2,g3); cout<<i<<endl; cout<<d<<endl; cout<<g<<endl; return 0; } //使用变量的引用来传递值进行转换，也可以传递地址，使用指针获取地址再使用 //变量的引用 1.12 #include "iostream" using namespace std; int swap(int &a,int &b){ return a>b?a:b; } int main(){ int n,m; cin>>n>>m; cout<<swap(n,m); return 0; } //一个简单的类 2.4 #include "iostream" #include "algorithm" using namespace std; class Array_max{ public: void set_value(); void max_value(); void show_value(); private: int array[100]; int maxn; }; void Array_max::set_value(){ for(int i=0;i<10;i++){ cin>>array[i]; } } void Array_max::max_value(){ sort(array,10); maxn = array[9]; } void Array_max::show_value(){ cout<<"max="<<maxn<<endl; } int main(){ Array_max arr; arr.set_value(); arr.max_value(); arr.show_value(); return 0; } 简单的构造函数 3.1 #include "iostream" using namespace std; class Time{ public: Time(){ hour = minute = sec = 0;} void set_time(); void show_time(); private: int hour; int minute; int sec; }; void Time::set_time(){ cin>>hour>>minute>>sec; } void Time::show_time(){ cout<<hour<<":"<<minute<<":"<<sec<<endl; } int main(){ Time t; t.show_time(); return 0; } 类外定义有参的构造函数 3.2 #include "iostream" using namespace std; class Time{ public: Time(int,int,int); void set_time(); void show_time(); private: int hour; int minute; int sec; }; void Time::set_time(){ cin>>hour>>minute>>sec; } void Time::Time(int h,int m,int s){ hour = h; minute = m; sec = s; } void Time::show_time(){ cout<<hour<<":"<<minute<<":"<<sec<<endl; } int main(){ Time t; t.show_time(); return 0; } 使用默认参数的构造函数 3.4 #include "iostream" using namespace std; class Box{ public: Box(int h=0,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; weigth = w; length = len; } int Box::volume(){ return height*weigth*length; } int main(){ Box box1; cout<<box1.volume()<<endl; Box box2(15); cout<<box2.volume()<<endl; Box box3(15,30); cout<<box3.volume()<<endl; Box box4(15,30,20); cout<<box4.volume()<<endl; return 0; } 析构函数 3.5 #include "iostream" #include "string" 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 dispaly(){ cout<<"num: "<<num<<endl; cout<<"name: "<<name<<endl; cout<<"sex: "<<sex<<endl; } private: int num; string name; char sex; }; int main(){ Student stud1(10010,"Wang_li",'f'); stud1.dispaly(); Student stud2(10011,"Zhang_fan",'m'); stud2.dispaly(); return 0; } 对象指针： Time *pt; 定义指针 Time t1; 定义对象 pt = &t1; 将t1的起始地址给指针pt 指针对成员的引用 *pt (*pt).hour pt->hour 普通函数可以在类内声明为友元函数 friend void display(Time&); 其他类里的成员函数也可以在类内声明为友元函数 friend void Time::display(Date&) 注意括号里的内容，友元函数可以访问私有成员 最开始的复数相加，重载+运算符 4.2 其他符号的重载都相似，会一个就行 #include "iostream" using namespace std; class Complex{ public: Complex(){real = 0;imag = 0;} Complex(double r,double i){real = r;imag = i;} Complex operator +(Complex &c2); void display(); private: double real; double imag; }; Complex Complex::operator +(Complex &c2){ Complex c; c.real = real + c2.real; c.imag = imag + c2.imag; return c; } void Complex::display(){ cout<<real<<" : "<<imag<<endl; } int main(){ Complex c1(3,4),c2(5,-10),c3; c3 = c2 + c1; c3.display(); return 0; } 重载流插入运算符和流提取运算符 istream & operator >>(istream &,自定义类 &); ostream & operator <<(ostream &,自定义类 &); 重载流插入运算符 《 #include "iostream" using namespace std; class Complex{ public: Complex() {real = 0;imag = 0;} Complex(double r,double i){real = r;imag = i;} Complex operator +(Complex&c2); friend ostream& operator <<(ostream,Complex&); private: double real; double imag; }; Complex Complex::operator +(Complex&c2){ return Complex(real+c2.real,imag+c2.imag); } ostream & operator <<(ostream & output,Complex&c){ output<<"("<<c.real<<"+"<<c.imag<<"i)"<<endl; return output; } int main(){ Complex c1(2,4),c2(6,10),c3; c3 = c2 + c1; cout<<c3<<endl; return 0; } 重载流提取运算符 #include "iostream" using namespace std; class Complex{ public: friend ostream& operator <<(ostream&,Complex&); friend istream& operator >>(istream&,Complex&); private: double real; double imag; }; ostream& operator <<(ostream& output,Complex& c){ output<<c.real<<c.imag<<endl; return output; } istream& operator >>(istream& input,Complex& c){ input>>c.real>>c.imag; return input; } int main(){ Complex c1,c2; cin>>c1>>c2; cout<<c1<<endl; cout<<c2<<endl; return 0; } |