一个我觉得很有意思的C++泛型模版

练家志

#include <iostream>
using namespace std;

template <class T>
/*T mymax(T a,T b)
{
    return a>b?a:b;
}*/
      
template<int N>
struct Fib
{
    enum{Result = Fib<N-1>::Result+Fib<N-2>::Result};
};
template <>
struct Fib<1>
{
    enum{Result=1};
};
template <>
struct Fib<0>
{
    enum{Result=0};
};

template < bool b, typename T1, typename T2 >
struct _type_helper
{
    typedef T2 type;
};
template < typename T1, typename T2 >
struct _type_helper< true, T1, T2 >
{
    typedef T1 type;
};
template < typename T1, typename T2 >
struct large_type
{
    typedef typename _type_helper< ( sizeof(T1) > sizeof(T2) ), T1, T2 >::type type;
};
template < typename T1, typename T2 >
struct small_type
{
    typedef typename _type_helper< ( sizeof(T2) > sizeof(T1) ), T1, T2 >::type type;
};
template < typename T1, typename T2 >
typename small_type<T1,T2>::type auto_min( T1 a, T2 b )
{
    return (a < b ? a : b);
}
template < typename T1, typename T2 >
typename large_type<T1,T2>::type auto_max( T1 a, T2 b )
{
    return a > b ? a : b;
}
int main()
{
     int iFib=Fib<20>::Result;
    cout<<iFib<<endl;
    std::cout << auto_max( 'A', 66 ) << std::endl;
    std::cout << auto_min( 'A', 66 ) << std::endl;
    return 0;
}