看見別人的
帖子，也做了下。
代碼只支持內(nèi)建類型。
1
#include <iostream>
2
3template<bool, typename T, typename F>
4
struct Select_type 
{ typedef T R; };
5
6template<typename T, typename F>
7struct Select_type<false, T, F> { typedef F R; };
8
9template<typename T, typename S>
10struct Larger_type {
11
typedef typename Select_type<sizeof(T) >= sizeof(S), T, S>::R R;
12
};
13
14template<typename T, typename S>
15typename Larger_type<T, S>::R min_value(T a, S b)
16{
17 return a < b ? a : b;
18}
19
20
21int main()
22{
23 int a = 2;
24 double b = 1.2;
25 std::cout << min_value(a, b) << " " << min_value(b, a) << "\n";
26}
27
28
浮點(diǎn)數(shù)與整型進(jìn)行比較時(shí)，默認(rèn)整型轉(zhuǎn)為浮點(diǎn)數(shù)
template<bool, typename T, typename F>
struct Select_type { typedef T R; };
template<typename T, typename F>
struct Select_type<false, T, F> { typedef F R; };
template<typename T> struct Type_rank
{ static const int rank = 0; };
template<> struct Type_rank<float>
{ static const int rank = 21; };
template<> struct Type_rank<double>
{ static const int rank = 22; };
template<> struct Type_rank<long double>
{ static const int rank = 23; };
template<typename T, typename S>
struct Larger_type {
static const int fa = Type_rank<T>::rank;
static const int fb = Type_rank<S>::rank;
static const bool flag = fa > fb || (fa == fb && sizeof(T) >= sizeof(S));
typedef typename Select_type<flag, T, S>::R R;
};
template<typename T>
struct Larger_type<T, T> { typedef T R;};
template<typename T, typename S>
typename Larger_type<T, S>::R min_value(T a, S b)
{
return a < b ? a : b;
}