The open-content wikibook "More C++ Idioms" has grown quite a bit from it inception. Whenever I get time, I try to add more contents in the book. So I always wanted to track the changes happening in the book in a convenient manner. Today, I put together a RSS feed for the book, which publishes recent changes made to the book. Thanks to the excellent technical support provided by existing wikibookians (if that is a word). The feed is formatted like two column GUI-based diff utilities (kdiff3, Beyond-compare). Frankly, it is not as readable and enjoyable as regular blog entries but at least it will help interested readers to know what new content is being added to the book and how the book making progress towards completion.
What new can be said about multi-dimensional arrays in C++? As it turns out, quite a bit! With the advent of C++11, we get new standard library class std::array. We also get new language features, such as template aliases and variadic templates. So I'll talk about interesting ways in which they come together.
It all started with a simple question of how to define a multi-dimensional std::array. It is a great example of deceptively simple things. Are the following the two arrays identical except that one is native and the other one is std::array?
int native[3][4];
std::array<std::array<int, 3>, 4> arr;
No! They are not. In fact, arr is more like an int[4][3]. Note the difference in the array subscripts. The native array is an array of 3 elements where every element is itself an array of 4 integers. 3 rows and 4 columns. If you want a std::array with the same layout, what you really need is:
std::array<std::array<int, 4>, 3> arr;
That's quite annoying for two r…
It all started with a simple question of how to define a multi-dimensional std::array. It is a great example of deceptively simple things. Are the following the two arrays identical except that one is native and the other one is std::array?
int native[3][4];
std::array<std::array<int, 3>, 4> arr;
No! They are not. In fact, arr is more like an int[4][3]. Note the difference in the array subscripts. The native array is an array of 3 elements where every element is itself an array of 4 integers. 3 rows and 4 columns. If you want a std::array with the same layout, what you really need is:
std::array<std::array<int, 4>, 3> arr;
That's quite annoying for two r…
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