[C++知识库]C++模板和STL

例：

#include <iostream>
using namespace std;

//函数模板,"T"类型形参
template <typename T>   //推荐使用typename 
//template <class T>
T max(T x, T y){
  return x<y?y:x;
}
int main(void){
  int  i1=100,i2=200;
  // "<>"指明函数模板需要的类型实参
  // "()"指明函数的调用实参
  cout<<::max<int>(i1,i2)<<endl;

  double d1=1.23,d2=4.56;
  cout<<::max<double>(d1,d2)<<endl;

  string s1="world",s2 = "hello";
  cout<<::max<string>(s1,s2)<<endl;

  char str1[] = "world";
  char str2[] = "hello";
  cout<<::max<string>(str1,str2)<<endl;
  return 0;

}

参考代码：

#include <iostream>
using namespace std;
template <typename T>
T add(T x,T y){
  return x+y;
}
class Complex{ //复数
public:
      Complex(int r,int i):m_r(r),m_i(i){}
      //cout<<c1==>operator<<(cout,c1)	
      friend ostream& operator<<(ostream& os,const Complex& c){
        os<<c.m_r<<"+" <<c.m_i<<"i";
	return os;
      }
      //重载+ (成员函数形式)
      //c1+c2 ==>c1.operator(c2)
      const Complex operator+(const Complex& c)const{
        Complex res(m_r+c.m_r,m_i+c.m_i);
	return res;
      }
private:
      int m_r;
      int m_i;
};

int main(void){
  cout<<add<int>(123,456)<<endl;
  cout<<add<double>(1.23,4.56)<<endl;
  Complex c1(1,2);
  Complex c2(3,4);
  cout<<c1<<","<<c2<<endl;
  cout<<add<Complex>(c1,c2)<<endl;  //4+6i
}