day-8 代码

string类

class String
{
public:                                 
   String(const char* cstr=0);                     
   String(const String& str);                    
   String& operator=(const String& str);         
   ~String();                                    
   char* get_c_str() const { return m_data; }
private:
   char* m_data;
};

inline
String::String(const char* cstr)
{
   if (cstr) {
      m_data = new char[strlen(cstr)+1];
      strcpy(m_data, cstr);
   }
   else {   
      m_data = new char[1];
      *m_data = '\0';
   }
}

inline
String::~String()
{
   delete[] m_data;
}

ostream& operator<<(ostream& os, const String& str)
{
   os << str.get_c_str();
   return os;
}

静态函数&静态变量

class Account {
public:
	static double m_rate;
	static void set_rate(const double& x) { m_rate = x; }
};
double Account::m_rate = 8.0;

int main()
{
  Account::set_rate(5.0);
	Account a;
	a.set_rate(7.0);
}

类模板

template<typename T>
class complex
{
public:
	complex(T r, T i = 0):re(r), im(i)
	{}
	T real() const { return re; }
	T imag() const { return im; }
	int func(const complex& param)
	{
		return param.im + param.re;
	}
	complex& operator += (const complex& r)
	{
		return _doapl(this, r);
	}
private:
	T re, im;
	//返回值为complex不是void，为了防止c3 += c2 += c1不能执行
	friend complex& _doapl(complex* ths, const complex& r)
	{
		ths->re += r.re;
		ths->im += r.im;
		return *ths;
	}
};

//返回ostream的os类型，是为了连续输出 cout<<c1<<conj(c1);
//不能是void类型，void类型满足单次输出
//ostream& operator << (ostream& os, const complex& x)
//{
//	return os << "(" << x.real() << "+" << x.imag() << 'i'
//		<< ")";
//}
//ostream& operator << (ostream& os, const complex& x)
//{
//	return os << "(" << x.real() << "+" << x.imag() << 'i'
//		<< ")";
//}


int main()
{
	complex<double> c1(2, 5);
	complex<int> c2(6);
	cout << c2.real() << " +i" << c2.imag() << endl;

	cout << endl;
	return 0;
}