Array
本章讨论array，重要参考如下两篇文章:
1) stackoverflow How do I use arrays in C++?
2) cppreference Array declaration
Pointer and array
Array to pointer decay
一维array会decay to 一级pointer，显然两者能够进行对应；static array vs dynamic array，其实dynamic array就是一个pointer；
因为array和memory的结构的相同：都是sequence，这就导致了两者的类似；
array和pointer有着相同的arithmetic；
上述两个相似点，导致了pointer和array的很多地方的相似；
Multidimensional array和multiple-level pointer有着对应关系的；可以使用一个multiple-level pointer来访问一个multidimensional array，典型的例子：
1 char **argv和char* argv[]
Multidimensional array和multiple-level pointer都可以使用containing关系来进行理解；
n-dimensional array、array of pointer、multiple-degree and n-dimensional array
https://stackoverflow.com/questions/4810664/how-do-i-use-arrays-in-c?noredirect=1&lq=1
Multidimensional arrays
参见 Multidimensional-array 章节。
With arrays, why is it the case that a[5] == 5[a]?
As Joel points out in Stack Overflow podcast #34, in C Programming Language (aka: K & R), there is mention of this property of arrays in C: a[5] == 5[a]
Joel says that it's because of pointer arithmetic but I still don't understand. Why does a[5] == 5[a]?
A
The C standard defines the [] operator as follows:
a[b] == *(a + b)
Therefore a[5] will evaluate to:
*(a + 5)
and 5[a] will evaluate to:
*(5 + a)
a is a pointer to the first element of the array. a[5] is the value that's 5 elements further from a, which is the same as *(a + 5), and from elementary school math we know those are equal (addition is commutative).
A
#include <iostream>
int main(int argc, char** argv)
{
std::cout << std::boolalpha << std::endl;
bool Equal = "ABCD"[2] == 2["ABCD"];
std::cout << Equal << std::endl;
Equal = 2["ABCD"] == 'C';
std::cout << Equal << std::endl;
Equal = "ABCD"[2] == 'C';
std::cout << Equal << std::endl;
}
Array class
1) Dynamic array: std::vector<T> since C++98
2) Static array: std::array since C++11