优雅的方式来初始化非静态数组成员

推荐答案 11月6日下午3:32，mathieu< mathieu.malate ... @ gmail.comwrote： On Nov 6, 3:32 pm, mathieu <[email protected]: 考虑以下（*）。有没有办法重写它以便 保持方便（当数组v被修改时N被重新计算） *和*编译:) 谢谢， -Mathieu （*） 模板< typename T，unsigned int N> struct Functor { T值[N]; }; int main（） { const double v [] = {0,1,4,9,16,25 ，36}; const unsigned int N = sizeof（v）/ sizeof（v [0]）; Functor< double，Nf = v; //将无法编译 // Functor< double，7f = {{0,1,4,9,16,25,36}}; //需要 手动计算7 ... 返回0; } Hi, Consider the following (*). Is there a way to rewrite it so that itremains convenient (N is being recomputed when array v is modified)*and* compiles :)Thanks,-Mathieu(*)template <typename T, unsigned int N>struct Functor{ T values[N];};int main(){ const double v[] = {0, 1, 4, 9, 16, 25, 36 }; const unsigned int N = sizeof(v) / sizeof(v[0]); Functor<double,Nf = v; // will not compile //Functor<double,7f = { {0, 1, 4, 9, 16, 25, 36 } }; // need tocompute 7 by hand... return 0;} 超级丑陋的解决方案： #define V {0,1,4,9,16,25,36} int main（） { const double v [] = V; const unsigned int N = sizeof（ v）/ sizeof（v [0]）; Functor< double，Nf = {V}; .... } Super-ugly solution: #define V {0, 1, 4, 9, 16, 25, 36 }int main(){const double v[] = V;const unsigned int N = sizeof(v) / sizeof(v[0]);Functor<double,Nf = { V };....} mathieu写道： mathieu wrote: 考虑以下（*）。有没有办法重写它以便 保持方便（当数组v被修改时N被重新计算） *和*编译:) 谢谢， -Mathieu （*） 模板< typename T，unsigned int N> struct Functor { T值[N]; }; Hi, Consider the following (*). Is there a way to rewrite it so that itremains convenient (N is being recomputed when array v is modified)*and* compiles :)Thanks,-Mathieu(*)template <typename T, unsigned int N>struct Functor{ T values[N];}; 添加此函数： 模板< class T，unsigned NFunctor< T，NmakeFunctor（T（& a）） [N]） { Functor< T，Nf; std :: copy（a，a + N，f.values） ; 返回f; } Add this function: template<class T, unsigned NFunctor<T,NmakeFunctor(T (&a)[N]){Functor<T,Nf;std::copy(a, a+N, f.values);return f;} > int main（ ） { const double v [] = {0,1,4,9,16,25,36}; const unsigned int N = sizeof（v）/ sizeof（v [0]）; Functor< double，Nf = v; //将无法编译 // Functor< double，7f = {{0,1,4,9,16,25,36}}; //需要 手动计算7 ... >int main(){ const double v[] = {0, 1, 4, 9, 16, 25, 36 }; const unsigned int N = sizeof(v) / sizeof(v[0]); Functor<double,Nf = v; // will not compile //Functor<double,7f = { {0, 1, 4, 9, 16, 25, 36 } }; // need tocompute 7 by hand... Functor< double，Nf = makeFunctor（v）; Functor<double,Nf = makeFunctor(v); > 返回0; } > return 0;} 最终代码： 模板< typename T，unsigned int N> struct Functor { T值[N]; }; #include< algorithm> template< typename T， unsigned int N> Functor< T，NmakeFunctor（T const（& a）[N]） { Functor< T， Nf; std :: copy（a，a + N，f.values）; 返回f; } int main（） { const double v [] = {0,1,4,9,16,25,36} ; const unsigned int N = sizeof（v）/ sizeof（v [0]）; Functor< double，Nf = makeFunctor（v）; 返回0; } V - 请删除资金''A'通过电子邮件回复 我没有回复最热门的回复，请不要问 Final code: template <typename T, unsigned int N>struct Functor{T values[N];}; #include <algorithm>template <typename T, unsigned int N>Functor<T,NmakeFunctor(T const (&a)[N]){Functor<T,Nf;std::copy(a, a + N, f.values);return f;} int main(){const double v[] = {0, 1, 4, 9, 16, 25, 36 };const unsigned int N = sizeof(v) / sizeof(v[0]); Functor<double,Nf = makeFunctor(v); return 0;} V--Please remove capital ''A''s when replying by e-mailI do not respond to top-posted replies, please don''t ask 11月6日，3：晚上51点，Victor Bazarov < v.Abaza ... @ comAcast.netwrote： On Nov 6, 3:51 pm, "Victor Bazarov" <[email protected]: mathieu写道： mathieu wrote: Hi, 考虑以下（*）。有没有办法重写它以便 保持方便（当数组v被修改时N被重新计算） *和* compiles :) Consider the following (*). Is there a way to rewrite it so that it remains convenient (N is being recomputed when array v is modified) *and* compiles :) .... .... 最终代码： template< typename T，unsigned int N> struct Functor { T values [N]; }; #include< algorithm> 模板< typename T，unsigned int N> Functor< T ，NmakeFunctor（T const（& a）[N]） { Functor< T，Nf; std :: copy（ a，a + N，f.values）; 返回f; } int main（） { const double v [] = {0,1,4,9,16,25,36}; const unsigned int N = sizeof （v）/ sizeof（v [0]）; Functor< double，Nf = makeFunctor（v）; 返回0; } Final code: template <typename T, unsigned int N> struct Functor { T values[N]; }; #include <algorithm> template <typename T, unsigned int N> Functor<T,NmakeFunctor(T const (&a)[N]) { Functor<T,Nf; std::copy(a, a + N, f.values); return f; } int main() { const double v[] = {0, 1, 4, 9, 16, 25, 36 }; const unsigned int N = sizeof(v) / sizeof(v[0]); Functor<double,Nf = makeFunctor(v); return 0; } 美观简单！ 谢谢， -Mathieu nice and simple ! Thanks,-Mathieu 这篇关于优雅的方式来初始化非静态数组成员的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！