1. 容器类介绍
1.1. 容器介绍
（1）容器是盛放东西的东西，这里被盛放的一般是数据对象，用来盛放的是容器类
（2）C语言语法内置的数组与结构体，就是语言源生支持的容器
（3）C++容器通过类库的方式提供，容器类库被模板技术泛化后，就是STL容器了
1.2. STL中的容器类
（1）序列容器。元素在容器中的位置与元素的值无关，容器是不排序的（类似C数组），包括array、vector、deque、list、forward_list等几个
（2）排序容器。数据插入时即自动按照值从小到大排列好，包括set、multiset、map、multimap等
（3）哈希容器。哈希容器中的元素是未排序的，元素的位置由哈希函数确定，即遵守一定规则的<key, value>对式存储，包括unordered_set、unordered_map、hash_set、hash_multiset、hash_map、hash_multimap
2. 容器类array的初步使用
2.1. array的特性
（1）array 是定长、同类型多元素、内存中连续排布的一种容器
（2）array其实就是C语言数组的C++ template封装
2.2. array的构造与初始化
1 #include <iostream> 2 #include <array> 3 4 using namespace std; 5 6 int main(void) 7 { 8 9 array<int, 3> a1; //正确，定义了未初始化，值是随机的 10 //array<int, 3> a2(1, 4, 5); //错误，C++无法提供无数个构造函数来匹配 11 array<int, 3> a3{1, 4, 5}; //正确，属于聚合初始化 12 array<int, 3> a4 = {1, 4, 5}; //正确，初始化赋值 13 array<int, 3> a5 = a4; //拷贝构造 14 15 return 0; 16 }
2.3. array的元素访问
（1）at方法
（2）operator[]实现的C数组式访问
（3）front和back方法返回第1个和最后1个元素
（4）data返回真实存储内存中首元素首地址的值
2.4. array的容量设置和获取
（1）容量设置只能在定义时一次设定，且必须设定，设定后不能修改
（2）empty
（3）size
（4）max_size
1 #include <iostream> 2 #include <array> 3 4 using namespace std; 5 6 int main(void) 7 { 8 array<int, 3> a1{2, 4, 6}; 9 10 cout << "a1.at(0) = " << a1.at(0) << endl; 11 cout << "a1.at(1) = " << a1.at(1) << endl; 12 cout << "a1.at(2) = " << a1.at(2) << endl; 13 14 cout << "a1[0] = " << a1[0] << endl; 15 cout << "a1[1] = " << a1[1] << endl; 16 cout << "a1[2] = " << a1[2] << endl; 17 18 cout << "a1.front() = " << a1.front() << endl; 19 cout << "a1.back() = " << a1.back() << endl; 20 21 int* p = a1.data(); 22 cout << "a1.data() = " << a1.data() << ", *p = " << *p << endl; 23 24 cout << "a1.empty() = " << a1.empty() << endl; 25 cout << "a1.size() = " << a1.size() << endl; 26 cout << "a1.max_size() = " << a1.max_size() << endl; 27 28 return 0; 29 } 30 31 /* 32 输出结果： 33 a1.at(0) = 2 34 a1.at(1) = 4 35 a1.at(2) = 6 36 a1[0] = 2 37 a1[1] = 4 38 a1[2] = 6 39 a1.front() = 2 40 a1.back() = 6 41 a1.data() = 0x7ffc0b2328ec, *p = 2 42 a1.empty() = 0 43 a1.size() = 3 44 a1.max_size() = 3 45 */
2.5. array的fill和swap操作
（1）fill
以指定值填充容器
（2）swap
交换内容
1 #include <iostream> 2 #include <array> 3 4 using namespace std; 5 6 int main(void) 7 { 8 array<int, 5> a1{1, 2, 3, 2, 5}; 9 10 cout << "a1[0] = " << a1[0] << endl; 11 cout << "a1[1] = " << a1[1] << endl; 12 cout << "a1[2] = " << a1[2] << endl; 13 cout << "a1[3] = " << a1[3] << endl; 14 cout << "a1[4] = " << a1[4] << endl; 15 array<int, 5> b1{6, 6, 6, 6, 6}; 16 a1.swap(b1); 17 cout << "a1[0] = " << a1[0] << endl; 18 cout << "a1[1] = " << a1[1] << endl; 19 cout << "a1[2] = " << a1[2] << endl; 20 cout << "a1[3] = " << a1[3] << endl; 21 cout << "a1[4] = " << a1[4] << endl; 22 a1.fill(5); 23 cout << "a1[0] = " << a1[0] << endl; 24 cout << "a1[1] = " << a1[1] << endl; 25 cout << "a1[2] = " << a1[2] << endl; 26 cout << "a1[3] = " << a1[3] << endl; 27 cout << "a1[4] = " << a1[4] << endl; 28 29 return 0; 30 } 31 32 /*输出结果： 33 a1[0] = 1 34 a1[1] = 2 35 a1[2] = 3 36 a1[3] = 2 37 a1[4] = 5 38 a1[0] = 6 39 a1[1] = 6 40 a1[2] = 6 41 a1[3] = 6 42 a1[4] = 6 43 a1[0] = 5 44 a1[1] = 5 45 a1[2] = 5 46 a1[3] = 5 47 a1[4] = 5 48 */
2.6. array的非成员函数使用
（1）operator函数重载
1 #include <iostream> 2 #include <array> 3 4 using namespace std; 5 6 int main(void) 7 { 8 array<int, 3> a1{1, 3, 5}; 9 array<int, 3> a2{2, 4, 6}; 10 11 cout << "a1 == a2 ?" << (a1 == a2) << endl; 12 cout << "a1 > a2 ? " << (a1 > a2) << endl; 13 cout << "a1 < a2 ? " << (a1 < a2) << endl; 14 15 return 0; 16 } 17 18 /* 19 输出结果： 20 a1 == a2 ?0 21 a1 > a2 ? 0 22 a1 < a2 ? 1 23 */
（2）get
从array中提取第I个元素，且I必须是范围[0, N)中的整数值
1 #include <iostream> 2 #include <array> 3 4 using namespace std; 5 6 int main(void) 7 { 8 array<int, 3> a1{1, 3, 5}; 9 array<int, 3> a2{2, 4, 6}; 10 11 int x = 0; 12 x = get<0, int, 3>(a1); 13 cout << "x = " << x << endl; 14 15 x = get<1, int, 3>(a1); 16 cout << "x = " << x << endl; 17 18 x = get<2, int, 3>(a1); 19 cout << "x = " << x << endl; 20 21 return 0; 22 } 23 24 /* 25 输出结果： 26 x = 1 27 x = 3 28 x = 5 29 */
（3）swap
1 #include <iostream> 2 #include <array> 3 4 using namespace std; 5 6 int main(void) 7 { 8 array<int, 3> a1{1, 2, 3}; 9 array<int, 3> a2{2, 4, 8}; 10 11 swap<int, 3>(a1, a2); 12 13 cout << "a[0] = " << a1[0] << endl; 14 cout << "a[1] = " << a1[1] << endl; 15 cout << "a[2] = " << a1[2] << endl; 16 17 return 0; 18 } 19 20 /* 21 输出结果： 22 a[0] = 2 23 a[1] = 4 24 a[2] = 8 25 */
（4）to_array(C++20)
将一个C数组转换为C++中的array
std::to_array("foo"); //创建std:: array<char, 4>{‘f‘, ‘o‘, ‘o‘, ‘\0‘}
std::array{"foo"}; //创建std::array<const char*, 1>{+"foo"}
1 #include <iostream> 2 #include <array> 3 4 using namespace std; 5 6 int main(void) 7 { 8 int a[3] = {1, 3, 5}; 9 array<int, 3> b = to_array<int, 3>(a); 10 11 cout << "b[0] = " << b[0] << endl; 12 cout << "b[1] = " << b[1] << endl; 13 cout << "b[2] = " << b[2] << endl; 14 15 return 0; 16 }
原文：https://www.cnblogs.com/Ramentherapy/p/14403847.html
