STL 容器简介

1#include <iostream>
2#include <vector>
3
4int main() {
5    // 1. 创建整数向量
6    std::vector<int> numbers = {10, 20, 30};
7
8    // 2. 动态添加元素
9    numbers.push_back(40); // 大小自动增加
10    numbers.push_back(50);
11
12    // 3. 访问元素
13    std::cout << "第一个元素: " << numbers[0] << "\n";
14    std::cout << "当前大小: " << numbers.size() << "\n";
15
16    // 4. 使用 .at() 安全访问（越界时抛出异常）
17    std::cout << numbers.at(1) << "\n"; 
18}

1#include <iostream>
2#include <vector>
3
4int main() {
5    std::vector<int> nums = {10, 20, 30};
6
7    // 有效访问
8    std::cout << nums[1] << std::endl;      // 输出: 20
9    std::cout << nums.at(1) << std::endl;   // 输出: 20
10
11    std::cout << nums[5] << std::endl;      // 未定义行为
12    std::cout << nums.at(5) << std::endl;   // 抛出 std::out_of_range
13}

1#include <iostream>
2#include <array>
3
4int main() {
5    // std::array<Type, Size>
6    std::array<int, 3> point = {1, 2, 3};
7
8    std::cout << "大小: " << point.size() << "\n"; // 始终为 3
9
10    // 我们可以修改值，但无法添加或删除元素
11    point[0] = 100; 
12    // point.push_back(4); // 错误: std::array 大小固定
13    
14    for (int value : point) {
15        std::cout << "元素: " << value << " ";
16    }
17    
18    std::cout << "\n";
19}

1#include <iostream>
2#include <deque>
3
4int main() {
5    std::deque<int> history;
6
7    history.push_back(1);  // [1]
8    history.push_back(2);  // [1, 2]
9    
10    // 高效地在前端插入
11    history.push_front(0); // [0, 1, 2]
12
13    std::cout << "前端: " << history.front() << "\n"; // 0
14    std::cout << "后端: " << history.back() << "\n";   // 2
15}

1#include <iostream>
2#include <unordered_map>
3#include <string>
4
5int main() {
6    std::unordered_map<int, std::string> students;
7
8    students[101] = "Alice";
9    students[102] = "Bob";
10    students[103] = "Charlie";
11
12    std::cout << "学生 102: " << students[102] << "\n";
13
14    if (students.find(104) == students.end()) {
15        std::cout << "学生 104 未找到\n";
16    }
17
18    students.erase(103);
19
20    for (const auto& pair : students) {
21        std::cout << pair.first << ": " << pair.second << "\n";
22    }
23}

1#include <iostream>
2#include <map>
3#include <string>
4
5int main() {
6    std::map<std::string, int> shapes;
7
8    shapes["Circle"] = 5;
9    shapes["Square"] = 10;
10    shapes["Triangle"] = 8;
11
12    std::cout << "正方形: " << shapes["Square"] << "\n";
13
14    for (const auto& pair : shapes) {
15        std::cout << pair.first << ": " << pair.second << "\n";
16    }
17}

1#include <iostream>
2#include <stack>
3
4int main() {
5    std::stack<int> numbers;
6
7    numbers.push(10);
8    numbers.push(20);
9    numbers.push(30);
10
11    std::cout << "顶部: " << numbers.top() << "\n";
12
13    numbers.pop();
14
15    std::cout << "弹出后顶部: " << numbers.top() << "\n";
16}

1#include <iostream>
2#include <queue>
3
4int main() {
5    std::queue<int> tasks;
6
7    tasks.push(1);
8    tasks.push(2);
9    tasks.push(3);
10
11    std::cout << "前端: " << tasks.front() << "\n";
12
13    tasks.pop();
14
15    std::cout << "弹出后前端: " << tasks.front() << "\n";
16}