blocks|key|3119597|text|如果你想学习C%2B%2B，首先要学习C%2B%2B11，之前的C%2B%2B标准是在2003年发布的，这意味着它已经有十年的历史了。这在IT世界里是很多的。C%2B%2B11技能也将平滑地转换到即将到来的C%2B%2B1y+(最有可能是C%2B%2B14)标准。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3119598|std::vector和std::array之间的主要区别在于动态存储(在大小和分配方面)和静态存储。所以，如果你想要一个矩阵类，比如说，4x4，std::array<float,+4*4>就行了。|offset|length|style|CODE|3119599|这两个类都提供了.data()成员，它应该会产生一个兼容的指针。但是请注意，std::vector<std::vector<float>>不会占用连续的16*sizeof(float)内存(因此v[0].data()+不会工作)。如果您需要一个动态调整大小的矩阵，请使用单个vector并将其大小调整为width*height大小。|BOLD|3119600|由于对元素的访问会稍微困难一些(v[width+*+y+%2Bx]或v[height+*+x+%2B+y])，因此您可能希望提供一个包装类，允许您按行/列对访问任意字段。|3119601|由于您还提到了C风格的数组；std::array提供了更好的接口来处理相同类型的存储，因此应该优先使用；与std::array相比，使用静态数组没有什么好处。|3119602|entityMap^0|0|0|B|C|A|21|M|0|8|7|12|V|24|G|2P|B|3T|6|47|C|31|2|0|G|F|W|H|0|E|A|1H|A|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@$D|S|E|T|F|G]|$D|U|E|V|F|G]|$D|W|E|X|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|Y|8|@$D|Z|E|10|F|G]|$D|11|E|12|F|G]|$D|13|E|14|F|G]|$D|15|E|16|F|G]|$D|17|E|18|F|G]|$D|19|E|1A|F|G]|$D|1B|E|1C|F|J]]|9|@]|A|$]]|$1|K|3|L|5|6|7|1D|8|@$D|1E|E|1F|F|G]|$D|1G|E|1H|F|G]]|9|@]|A|$]]|$1|M|3|N|5|6|7|1I|8|@$D|1J|E|1K|F|G]|$D|1L|E|1M|F|G]]|9|@]|A|$]]|$1|O|3|-4|5|6|7|1N|8|@]|9|@]|A|$]]]|P|$]]

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.

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

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

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

Since you've also mentioned C-style arrays; <code>std::array</code> 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 <code>std::array</code>.

blocks|key|860174|text|这是对这个问题的很晚的回答，但是如果有人读了这篇文章，我只想指出，一个人几乎永远不应该将矩阵实现为“向量的向量”。原因是矩阵的每一行都存储在堆上的某个随机位置。这意味着矩阵操作将进行大量随机内存访问，从而导致缓存未命中，这会大大减慢实现速度。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|860175|换句话说，如果您非常关心性能，只需分配一个大小为rows+*+columns的array/std::array/std::vector，然后使用包装器函数将一对整数转换为数组中的相应元素。除非您需要支持像返回对矩阵的行的引用这样的东西，否则所有这些选项都应该可以很好地工作。|offset|length|style|CODE|860176|entityMap^0|0|O|E|13|S|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@$D|L|E|M|F|G]|$D|N|E|O|F|G]]|9|@]|A|$]]|$1|H|3|-4|5|6|7|P|8|@]|9|@]|A|$]]]|I|$]]

This is a very late reply to the question, but if someone reads this, I just want to point out that one should almost never implement a matrix as a ''vector of vectors''. The reason is that each row of the matrix gets stored in some random location on the heap. This means that matrix operations will do a lot of random memory accesses leading to cache misses, which slows down the implementation considerably.

In other words, if you care at all about performance, just allocate an <code>array/std::array/std::vector</code> of size <code>rows * columns</code>, then use wrapper functions that transforms a pair of integers to the corresponding element in the array. Unless you need to support things like returning references to rows of the matrix, then all of these options should work just fine.

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

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

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

But with C++11 it is possible to use std::array. According to this <a href="http://en.cppreference.com/w/cpp/container/array" rel="noreferrer">site</a>, this container seems to be the best solution... What do you think?

c++11 std::array vs static array vs std::vector

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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第一个问题是，如果我将在接下来的3年里开发代码，那么开始使用c++11是一件好事吗？如果是这样，如果我想在Lapack中使用矩阵，那么实现矩阵的“最佳”方式是什么？我的意思是，做std::vector<std::vector< Type > > Matrix并不容易与Lapack兼容。到目前为止，我用Type* Mat...

问c++11 std::array vs静态数组vs std::vector
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