C++基本語法操作方式

• 
  #include "stdafx.h"
  
  #include <iostream>
  #include <string>
  #include <stdlib.h>
  
  using namespace std;
  
  
  //template
  template <typename T>
  
  T max(T a, T b)
  {
  	if (a > b)	return a;
  	else return b;
  }
  
  //default parameter
  int max_int(int a=1, int b=2)
  {
  	if (a > b) return a;
  	else return b;
  }
  
  enum test_enum
  {
  	item0,
  	item1,
  	item2,
  };
  
  
  //class test
  
  class student;	//提前聲明
  
  class student
  {
  
  private:
  	int num;		//member variables
  	string name;
  	string sex;
  	mutable int mutable_var;		//mutable variable
  
  public:
  	const static int static_var;			//static variable
  
  public:
  	void display();					//normal member function
  	void const_display() const;		//const type member function
  	void const_display2() const;
  
  	bool operator > (student &stu) const;	// '>' operator reload
  	operator int() const;		//type conversion function of 'int'
  
  	friend void class_friend_function(student &a);	//friend function
  
  	student(int num, string name="null", string sex="null");	//constructor reload and with default parameters
  	student();		//constructor reload
  	virtual ~student();		//destructor
  };
  
  void student::display() 	//member function
  {
  	mutable_var = 1;	//mutable variable can be accessed in any function
  
  	cout << "display called" << endl;
  	cout << "num:" << num << ",name:" << name << ",sex:" << sex << endl;
  }
  
  void student::const_display2() const
  {
  	cout << "const_display2" << endl;
  }
  
  void student::const_display() const
  {
  	mutable_var = 1;	//const function can only modify mutable variable
  	const_display2();	//const function can only call const function
  
  	cout << "const display called" << endl;
  	cout << "num:" << num << ",name:" << name << ",sex:" << sex << endl;	//can refer to any member variables, dont change value
  }
  
  student::student(int num, string name, string sex)	//with default parameters
  {
  	this->num = num;
  	this->name = name;
  	this->sex = sex;
  
  	cout << "reload constructor" << endl;
  }
  
  student::student()	//constructor reload
  {
  	num = 2;
  	name = "wangming";
  	sex = "male";
  
  	cout << "default constructor" << endl;
  }
  
  student::~student()
  {
  	cout << "student destructor call" << endl;
  }
  
  //init static variable
  const int student::static_var = 0x55;
  
  //friend function
  void class_friend_function(student &a)
  {
  	cout << "class student friend function test:" << a.num << endl;
  }
  
  bool student::operator>(student &stu) const
  {
  	if (this->num >= stu.num) return true;
  	else return false;
  }
  
  student::operator int() const
  {
  	return num;
  }
  
  
  //derived class
  class student_derived :public student
  {
  private:
  	int derive_data;
  
  public:
  	void derive_function(void);
  	void display(void);
  
  	student_derived(int num=0, string name = "null", string sex = "null", int data = 0) :student(num, name, sex), derive_data(data){};
  	~student_derived(){};
  };
  
  void student_derived::display(void)
  {
  	cout << "derived class function overload" << endl;
  }
  void student_derived::derive_function(void)
  {
  	cout << "in derive_function" << endl;
  }
  
  
  int _tmain(int argc, _TCHAR* argv[])
  {
  	int sum, a, b;
  	string str;
  
  	const student student1(1, "name", "sex");
  	student student2;
  	student1.const_display();
  	cout << "static var=" << student::static_var <<","<<student1.static_var<< endl;
  	class_friend_function(student2);
  	cout << "class < operator reload=" << (student1 > student2) << endl;
  	cout << "type conversion function=" << int(student1) << endl;
  
  	student_derived stu1;
  	stu1.display();
  
  	cout << "this is a c++ program"<<endl<<"input a, b to add..."<<endl;
  
  	cin >> a >> b;
  	sum = a + b;
  	cout << "a+b=" << sum << endl;
  
  	cout << "template T max(T a,T b) return " << max(a,b) << endl;
  	cout << "default parameter max(a=1,b=2) return" << max_int() << endl;
  
  	str = "string";
  	cout << "string type=" << str <<",sizeof(str)="<<sizeof(str)<< endl;
  
  	system("pause");
  
  	return 0;
  }