模板学习实践一 accumulationtraits
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 | // 11111.cpp : 定义控制台应用程序的入口点。 // #include "stdafx.h" #include <iostream> #include <string> template<typename T> class AccumulationTraits; template<> class AccumulationTraits< char > { public : typedef int Acct; static Acct zero() { return 0; } }; template<> class AccumulationTraits< int > { public : typedef long Acct; static Acct zero() { return 0; } }; template<> class AccumulationTraits< float > { public : typedef double Acct; static Acct zero() { return 0; } }; /* template<typename T,typename AT = AccumulationTraits<T> > class Accum { public: static typename AT::Acct accum(T const* beg, T const* end) { typename AT::Acct total = AT::zero(); while (beg != end) { total += *beg; ++beg; } return total; } }; template<typename T> typename AccumulationTraits<T>::Acct accum(T const* beg, T const* end) { std::cout << "T" << std::endl; return Accum<T>::accum(beg,end); } template<typename Traits, typename T> typename AccumulationTraits<T>::Acct accum(T const* beg, T const* end) { std::cout << "T Traits" << std::endl; return Accum<T,Traits>::accum(beg, end); } */ template<typename T1, typename T2> class SumPolicy { public : static void accumulate(T1& total, T2 const & value) { total += value; } }; template<typename T, template<typename,typename> class Policy = SumPolicy, typename Traits = AccumulationTraits<T> > class Accum { public : typedef typename Traits::Acct Acct; static Acct accum(T const * beg,T const * end) { Acct total = Traits::zero(); while (beg != end) { Policy<Acct, T>::accumulate(total, *beg); ++beg; } return total; } }; int main() { int num[] = { 1,2,3,4,5 }; std::cout << Accum< int >::accum(&num[0],&num[5]) << std::endl; return 0; } |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 | // 11111.cpp : 定义控制台应用程序的入口点。 // #include "stdafx.h" #include <iostream> #include <string> template < typename T> class AccumulationTraits; template <> class AccumulationTraits< char > { public : typedef int Acct; static Acct zero() { return 0; } }; template <> class AccumulationTraits< int > { public : typedef long Acct; static Acct zero() { return 0; } }; template <> class AccumulationTraits< float > { public : typedef double Acct; static Acct zero() { return 0; } }; /* template<typename T,typename AT = AccumulationTraits<T> > class Accum { public: static typename AT::Acct accum(T const* beg, T const* end) { typename AT::Acct total = AT::zero(); while (beg != end) { total += *beg; ++beg; } return total; } }; template<typename T> typename AccumulationTraits<T>::Acct accum(T const* beg, T const* end) { std::cout << "T" << std::endl; return Accum<T>::accum(beg,end); } template<typename Traits, typename T> typename AccumulationTraits<T>::Acct accum(T const* beg, T const* end) { std::cout << "T Traits" << std::endl; return Accum<T,Traits>::accum(beg, end); } */ template < bool b = true > class SumPolicy { public : template < typename T1, typename T2> static void accumulate(T1& total, T2 const & value) { total += value; } }; template <> class SumPolicy< false > { public : template < typename T1, typename T2> static void accumulate(T1& total, T2 const & value) { total = total+value; } }; template < typename T, typename Policy = SumPolicy<>, typename Traits = AccumulationTraits<T> > class Accum { public : typedef typename Traits::Acct Acct; static Acct accum(T const * beg, T const * end) { Acct total = Traits::zero(); while (beg != end) { Policy::accumulate(total, *beg); ++beg; } return total; } }; int main() { int num[] = { 1,2,3,4,5 }; std::cout << Accum< int >::accum(&num[0], &num[5]) << std::endl; std::cout << Accum< int ,SumPolicy< false >>::accum(&num[0],&num[5]) << std::endl; std::cout << Accum< int , SumPolicy< true >>::accum(&num[0], &num[5]) << std::endl; return 0; } |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 | // 111111.cpp : 定义控制台应用程序的入口点。 // #include "stdafx.h" #include <iostream> template < typename T> class IsFundaT { public : enum {Yes = 0,No=1}; }; #define MK_FUNDA_TYPE(T) \ template <> class IsFundaT<T> { \ public : \ enum {Yes =1,No=0}; \ }; MK_FUNDA_TYPE( void ) MK_FUNDA_TYPE( bool ) MK_FUNDA_TYPE( signed char ) MK_FUNDA_TYPE(unsigned char ) MK_FUNDA_TYPE( wchar_t ) MK_FUNDA_TYPE( signed short ) MK_FUNDA_TYPE(unsigned short ) MK_FUNDA_TYPE( signed int ) MK_FUNDA_TYPE(unsigned int ) MK_FUNDA_TYPE( signed long ) MK_FUNDA_TYPE(unsigned long ) #if LONGLONG_EXISTS MK_FUNDA_TYPE( signed long long ) MK_FUNDA_TYPE(unsigned long long ) #endif // LONGLONG_EXISTS MK_FUNDA_TYPE( float ) MK_FUNDA_TYPE( double ) MK_FUNDA_TYPE( long double ) //====================================================== template < typename T> void test(T const & t) { if (IsFundaT<T>::Yes) { std::cout << "T is fundamental type" << std::endl; } else { std::cout << "T is no fundamental type" << std::endl; } } class MyType{ }; int main() { int i = 9; auto ii = std::move(i); test(ii); test(7); test(MyType()); return 0; } |
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欢迎转帖 请保持文本完整并注明出处
技术博客 http://www.cnblogs.com/itdef/
B站算法视频题解
https://space.bilibili.com/18508846
qq 151435887
gitee https://gitee.com/def/
欢迎c c++ 算法爱好者 windows驱动爱好者 服务器程序员沟通交流
如果觉得不错,欢迎点赞,你的鼓励就是我的动力


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