std::array

成员函数

Iterators

//函数签名：// iterator begin() noexcept;// iterator end() noexcept;#include<iostream>#include<array>using namespace std;int main(){    array<int, 5> my_array = { 2,4,8,7,11 };    for (auto it = my_array.begin(); it != my_array.end(); it++)        cout << *it << " ";    return 0;}

输出：
2 4 8 7 11
PS:如果array为空，begin()返回值与end()一样

//函数签名：//reverse_iterator rbegin() noexcept;//reverse_iterator rend() noexcept;#include<iostream>#include<array>using namespace std;int main(){    array<int, 5> my_array = { 2,4,8,7,11 };    for (auto it = my_array.rbegin(); it != my_array.rend(); it++)        cout << *it << " ";    return 0;}

输出：
11 7 8 4 2

//函数签名://const_iterator cbegin() const noexcept;//const_iterator cend() const noexcpet;#include<iostream>#include<array>using namespace std;int main(){    array<int, 5> my_array = { 2,4,8,7,11 };    for (auto it = my_array.cbegin(); it != my_array.cend(); it++)        cout << *it << " ";    return 0;}

输出：
2 4 8 7 11

//函数签名://const_iterator crbegin() const noexcept;//const_iterator crend() const noexcept;#include<iostream>#include<array>using namespace std;int main(){    array<int, 5> my_array = { 2,4,8,7,11 };    for (auto it = my_array.crbegin(); it != my_array.crend(); it++)        cout << *it << " ";    return 0;}

输出：
11 7 8 4 2

Capacity

//函数签名//constexpr size_type size() noexcept;#include<iostream>#include<array>using namespace std;int main(){array<int, 5> my_ints;array<char, 5> my_chars;cout << my_ints.size() << endl;cout << sizeof(my_ints) << endl;cout << my_chars.size() << endl;cout << sizeof(my_chars) << endl;  return 0;}

输出：
5
20 5*4（int的字节大小）
5
5 5*1（char的字节大小）
PS:size() 总是等于第二个用来实例化模板的参数

//函数签名//constexpr size_type max_size() noexcept;#include<iostream>#include<array>using namespace std;int main(){    array<int, 5> my_ints;    cout << my_ints.size() << endl;    cout << my_ints.max_size() << endl;  return 0;}

输出：
5
5

//函数签名//constexpr bool empty() noexcept;#include<iostream>#include<array>using namespace std;int main(){array<int, 0> first_array;array<int, 10> second_array;cout << first_array.empty() << endl;cout << second_array.empty() << endl;return 0;}

输出：
1
0

Element access

//函数签名//reference operator[] (size_type n);#include<iostream>#include<array>using namespace std;int main(){    array<int, 10> my_array;    for (unsigned int i = 0; i != 10; i++)        my_array[i] = i;    for (unsigned int i = 0; i != 10; i++)        cout << my_array[i]<<" ";    cout << endl;    return 0;}

输出：
0 1 2 3 4 5 6 7 8 9

//函数签名//reference at ( size_type n );#include<iostream>#include<array>using namespace std;int main(){array<int, 10> my_array;for (unsigned int i = 0; i != 10; i++)my_array[i] = i+1;for (unsigned int i = 0; i != 10; i++)cout << my_array.at(i) << " ";cout << endl;return 0;}

输出：
1 2 3 4 5 6 7 8 9 10

//函数签名//reference front();//reference back();#include<iostream>#include<array>using namespace std;int main(){    array<int, 3> my_array = { 0,8,11 };    cout << my_array.front() << endl;    cout << my_array.back() << endl;    return 0;}

输出：
0
11
PS：对空的array调用front()或者back()会造成未定义行为

//函数签名// value_type* data() noexcept;#include<cstring>#include<iostream>#include<array>using namespace std;int main(){    const char* str = "my string";    // 注意这里是10 不是 9    array<char, 10> char_array;    memcpy(char_array.data(), str, 10);    cout << char_array.data() << endl;    return 0;}

输出：
my string

Modifiers

//函数签名// void fill (const value_type& val);#include<iostream>#include<array>using namespace std;int main(){    array<int, 8> my_array;    my_array.fill(8);    // 注意这里是10 不是 9    for (int i = 0; i != my_array.size(); i++)        cout << my_array[0] << " ";    return 0;}

输出：
8 8 8 8 8 8 8 8

//函数签名// void swap (array& x) noexcept(noexcept(swap(declval<value_type&>(),declval<value_type&>())));#include<iostream>#include<array>using namespace std;int main(){    array<int, 3> my_array1 = { 1,2,3 };    array<int, 3> my_array2 = { 3,2,1 };    for (int i = 0; i != my_array1.size(); i++)        cout << my_array1[i] << " ";    cout << endl;    for (int i = 0; i != my_array2.size(); i++)        cout << my_array2[i] << " ";    cout << endl;    my_array1.swap(my_array2);    for (int i = 0; i != my_array1.size(); i++)        cout << my_array1[i] << " ";    cout << endl;    for (int i = 0; i != my_array2.size(); i++)        cout << my_array2[i] << " ";    cout << endl;    return 0;}

输出：
1 2 3
3 2 1
3 2 1
1 2 3
PS：交换的两个array必须包含相同的类型和大小，与其他容器的swap()不同，array的swap()只需要线性时间

非成员函数

//函数签名//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;#include<iostream>#include<array>#include<tuple>using namespace std;int main(){    array<int, 3> my_array = { 1,2,3 };    tuple<int, int, int> my_tuple(1, 2, 3);    tuple_element<0, decltype(my_array)>::type my_element;    my_element = get<2>(my_array);    get<2>(my_array) = get<0>(my_array);    get<0>(my_array) = my_element;    cout << get<0>(my_array) << endl;    cout << get<0>(my_tuple) << endl;    return 0;}

输出：
3
1
PS：get()重载了tuple的同名函数

//函数签名//(1)//template <class T, size_T N>//bool operator== (const array<T, N>& lhs, const array<T, N>& rhs);//(2)//template <class T, size_T N>//bool operator!= (const array<T, N>& lhs, const array<T, N>& rhs);//(3)//template <class T, size_T N>//bool operator<  (const array<T, N>& lhs, const array<T, N>& rhs);//(4)//template <class T, size_T N>//bool operator<= (const array<T, N>& lhs, const array<T, N>& rhs);//(5)//template <class T, size_T N>//bool operator>  (const array<T, N>& lhs, const array<T, N>& rhs);//(6)//template <class T, size_T N>//bool operator>= (const array<T, N>& lhs, const array<T, N>& rhs);#include<iostream>#include<array>using namespace std;int main(){    array<int, 3> a_array = { 1,2,3 };    array<int, 3> b_array = { 1,2,3 };    array<int, 3> c_array = { 3,2,1 };    if (a_array == b_array)        cout << "a_array and b_array are equal" << endl;    if (b_array != c_array)        cout << "a_array and b_array are not equal" << endl;    if (b_array < c_array)        cout << "b_array is less than c_array" << endl;    if (c_array > b_array)        cout << "c_array is greater than b_array" << endl;    if (a_array <= b_array)        cout << "a_array is less than or equal to b_array" << endl;    if (a_array >= b_array)        cout << "a_array is greater than or equal to b_array" << endl;    return 0;}

输出：
a_array and b_array are equal
a_array and b_array are not equal
b_array is less than c_array
c_array is greater than b_array
a_array is less than or equal to b_array
a_array is greater than or equal to b_array
PS：array重载了关系操作运算符