C ++ 11的std ::阵VS静态数组VS的std ::矢量 [英] c++11 std::array vs static array vs std::vector

问题描述

第一个问题，是一件好事，开始使用C ++ 11，如果我将开发一个code为3年以下？

First question, is it a good thing to start using c++11 if I will develop a code for the 3 following years?

接着，如果是，什么是最好的方式来实现一个矩阵，如果我想与LAPACK使用它呢？我的意思是，做的std ::矢量＆lt;的std ::矢量＆lt;类型＆GT; ＆GT;矩阵是不容易LAPACK兼容。

Then if it is, what is the "best" way to implement a matrix if I want to use it with Lapack? I mean, doing std::vector<std::vector< Type > > Matrix is not easily compatible with Lapack.

到现在为止，我存储我的矩阵键入*矩阵（新类型[N]）（指针形式新和删除是很重要的，因为数组的大小并不像许多像5中给出，但作为一个变量）。

Up to now, I stored my matrix with Type* Matrix(new Type[N]) (the pointer form with new and delete were important because the size of the array is not given as a number like 5, but as a variable).

但随着C ++ 11，可以使用std ::数组。根据这一网站，这个容器似乎是最好的解决办法......做什么你觉得呢？

But with C++11 it is possible to use std::array. According to this site, this container seems to be the best solution... What do you think?

推荐答案

首先第一件事情，如果你要学习C ++，学习C ++ 11。在previous C ++标准是在2003年发布，这意味着它已经的 10 的岁。这是一个很大的IT世界。 C ++ 11的技能也将顺利转化为即将到来的C ++ 1Y（最可能是C ++ 14）标准。

First things first, if you are going to learn C++, learn C++11. The previous C++ standard was released in 2003, meaning it's already ten years old. That's a lot in IT world. C++11 skills will also smoothly translate to upcoming C++1y (most probably C++14) standard.

的std ::矢量和的std ::阵列之间的主要区别是动态的（大小和分配）和静态存储器。所以，如果你想有一个矩阵类，总是，也就是说，4×4，的std ::阵列＆LT;浮动，4×4方式＆gt; 会做得很好。

The main difference between std::vector and std::array is the dynamic (in size and allocation) and static storage. So if you want to have a matrix class that's always, say, 4x4, std::array<float, 4*4> will do just fine.

这两个类提供了。数据（）成员，它应该产生一个兼容的指针。但是请注意，的std ::矢量＆lt;的std ::矢量＆lt;浮动＆GT;＆GT; 将不occuppy连续 16 *的sizeof（浮动）内存（以便 v [0]。数据（） 不会的工作）。如果你需要一个动态调整的矩阵，用单矢量，并将其调整为宽*高尺寸

Both of these classes provide .data() member, which should produce a compatible pointer. Note however, that std::vector<std::vector<float>> will NOT occuppy contiguous 16*sizeof(float) memory (so v[0].data() won't work). If you need a dynamically sized matrix, use single vector and resize it to the width*height size.

由于访问内容将是一个有点困难（​​ v [宽* Y + X] 或 v [高* X + Y ] ），你可能想提供一个包装类，可以让你按行/列对访问任意字段。

Since the access to the elements will be a bit harder (v[width * y +x] or v[height * x + y]), you might want to provide a wrapper class that will allow you to access arbitrary field by row/column pair.

既然你也提到了C风格的数组; 的std ::阵列提供了更好的接口来处理同一类型的存储，因而应该是preferred;没有什么获得与静态数组结束了的std ::阵列。

Since you've also mentioned C-style arrays; std::array provides nicer interface to deal with the same type of storage, and thus should be preferred; there's nothing to gain with static arrays over std::array.

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