C++11 容器Array

array是一个固定大小的顺序容器，不能动态改变大小，array内的元素在内存中以严格的线性顺序存储
与普通数组声明存储空间大小[]的方式是一样有效的，只是加入了一些成员函数和全局函数[get (array)、operators (array)]，以便当作标准容器使用
零大小的array是有效的，但是不可以被成员函数front、back、data间接引用
array的swap是一个线性操作交换所有的元素，通常是非常低效的

Constructor:
.template < class T, size_t N > class array;

举例：
array<int,10> iArray={1,2,3,4,5,6,7,8,9,10};  

 

Member functions:

Iterators

begin	Return iterator to beginning
end	Return iterator to end
rbegin	Return reverse iterator to reverse beginning
rend	Return reverse iterator to reverse end
cbegin	Return const_iterator to beginning
cend	Return const_iterator to end
crbegin	Return const_reverse_iterator to reverse beginning
crend	Return const_reverse_iterator to reverse end

std::array<int,> arr = { , , , ,  };
std::cout << "arr contains:";
for ( auto it = arr.cbegin(); it != arr.cend(); ++it )
{
　　*it = 34;　　　　//error can't modify *it
　　arr.begin();　　//point to array first element
　　arr.front();　　//return the first element
　　arr.back();　　 //return the end element

　　std::cout << *it << std::endl;
}

Capacity

empty	Test whether list is empty
size	Return size
max_size	Return maximum size

Element access

operator[]	Access element
at	Access element
front	Access first element
back	Access last element
data	Get pointer to first data

注意：使用at程序崩溃时不会显示堆栈信息，尽量使用[]去array的值

 

back

data//返回指向array中第一个元素的指针

const char* cstr = "Test string";
std::array<char,> charray;
std::memcpy (charray.data(),cstr,);
std::cout << charray.data() << std::endl;//如果是char类型则打印值 Test string
//如果array中保存的是int
cout << iArray.data() << endl;//两者等效，等于打印出第一个元素的地址
cout << &charray << endl;  

array<string,> sArray={"hello","c++","I"};
for (auto it = sArray.cbegin(); it != sArray.cend(); ++it)
{
   cout << *it << '\t';//打印出hello  c++ I
}
cout << sArray.data() << endl;//打印地址  

Modifiers

fill	Fill array with value
swap	Swap content

fill

std::array<int, > arr;
arr.fill();
for (auto it = arr.begin(); it != arr.end(); it++)
{
    std::cout << " " << *it;
}

arr.assign();
for (auto it = arr.begin(); it != arr.end(); it++)
{
   std::cout << " " << *it;
}

OutPut:

34 34 34 34 34 5 5 5 5 5

swap

Global functions

get(array)	Get element (tuple interface) (function template )
operators (array)	Global relational operator functions for array

get(array)//Returns a reference to the Ith element of array arr.

函数原型：
.template <size_t I, class T, size_t N> T& get ( array<T,N>& arr ) noexcept;
.template <size_t I, class T, size_t N> T&& get ( array<T,N>&& arr ) noexcept;
.template <size_t I, class T, size_t N> const T& get ( const array<T,N>& arr ) noexcept;

Output:
first element in myarray: 30
first element in mytuple: 10

operators(array)

模板原型如下：

.template <class T, size_T N>
    bool operator== ( const array<T,N>& lhs, const array<T,N>& rhs );
.template <class T, size_T N>
    bool operator!= ( const array<T,N>& lhs, const array<T,N>& rhs );
.template <class T, size_T N>
    bool operator< ( const array<T,N>& lhs, const array<T,N>& rhs );
4template <class T, size_T N>
   bool operator> ( const array<T,N>& lhs, const array<T,N>& rhs );
.template <class T, size_T N>
    bool operator<= ( const array<T,N>& lhs, const array<T,N>& rhs );
.template <class T, size_T N>
    bool operator>= ( const array<T,N>& lhs, const array<T,N>& rhs );

  std::array<int,> a = {, , , , };
  std::array<int,> b = {, , , , };
  std::array<int,> c = {, , , , };
  if (a==b) std::cout << "a and b are equal\n";
  if (b!=c) std::cout << "b and c are not equal\n";
  if (b<c) std::cout << "b is less than c\n";
  if (c>b) std::cout << "c is greater than b\n";
  if (a<=b) std::cout << "a is less than or equal to b\n";
  if (a>=b) std::cout << "a is greater than or equal to b\n";  

Output:
a and b are equal
b and c are not equal
b is less than c
c is greater than b
a is less than or equal to b
a is greater than or equal to b