详解C++编程中类模板的相关使用知识

class Compare_int
{
public :
  Compare(int a,int b)
  {
   x=a;
   y=b;
  }
  int max( )
  {
   return (x>y)?x:y;
  }
  int min( )
  {
   return (x<y)?x:y;
  }
private :
  int x,y;
};

class Compare_float
{
public :
  Compare(float a,float b)
  {
   x=a;y=b;
  }
  float max( )
  {
   return (x>y)?x:y;
  }
  float min( )
  {
   return (x<y)?x:y;
  }
private :
  float x,y;
}

template <class numtype> //声明一个模板，虚拟类型名为numtype
class Compare //类模板名为Compare
{
public :
  Compare(numtype a,numtype b)
  {
   x=a;y=b;
  }
  numtype max( )
  {
   return (x>y)?x:y;
  }
  numtype min( )
  {
   return (x<y)?x:y;
  }
private :
  numtype x,y;
};

  template <class 类型参数名>

  Compare_int cmp1(4,7); // Compare_int是已声明的类

  Compare cmp(4,7); // Compare是类模板名

  Compare <int> cmp(4,7);

#include <iostream>
using namespace std;
template <class numtype>
//定义类模板
class Compare
{
  public :
  Compare(numtype a,numtype b)
  {x=a;y=b;}
  numtype max( )
  {return (x>y)?x:y;}
  numtype min( )
  {return (x<y)?x:y;}
  private :
  numtype x,y;
};
int main( )
{
  Compare<int > cmp1(3,7); //定义对象cmp1，用于两个整数的比较
  cout<<cmp1.max( )<<" is the Maximum of two integer numbers."<<endl;
  cout<<cmp1.min( )<<" is the Minimum of two integer numbers."<<endl<<endl;
  Compare<float > cmp2(45.78,93.6); //定义对象cmp2，用于两个浮点数的比较
  cout<<cmp2.max( )<<" is the Maximum of two float numbers."<<endl;
  cout<<cmp2.min( )<<" is the Minimum of two float numbers."<<endl<<endl;
  Compare<char> cmp3(′a′,′A′); //定义对象cmp3，用于两个字符的比较
  cout<<cmp3.max( )<<" is the Maximum of two characters."<<endl;
  cout<<cmp3.min( )<<" is the Minimum of two characters."<<endl;
  return 0;
}

7 is the Maximum of two integers.
3 is the Minimum of two integers.

93.6 is the Maximum of two float numbers.
45.78 is the Minimum of two float numbers.

a is the Maximum of two characters.
A is the Minimum of two characters.

 numtype Compare::max( ) {…} //不能这样定义类模板中的成员函数

  template <class numtype>
  numtype Compare<numtype>::max( )
  {
    return (x>y)?x:y;
  }

template <class 虚拟类型参数>

  template <class numtype> //注意本行末尾无分号
  class Compare
  {…}; //类体

  类模板名<实际类型名> 对象名;
  类模板名<实际类型名> 对象名(实参表列);

  Compare<int> cmp;
  Compare<int> cmp(3,7);

  template <class 虚拟类型参数>

  函数类型 类模板名<虚拟类型参数>::成员函数名(函数形参表列) {…}

  template <class T1,class T2>
  class someclass
  {…};

  someclass<int,double> obj;