当前位置：首页 > news >正文

C++STL之deque

news 来源：原创 2025/5/31 7:38:40

概念：本质是一个指针数组并且 deque数据的添加是没有内存移动的

deque对象创建

#include <iostream>
#include <deque>
using namespace std;// 辅助函数：打印deque内容
template<typename T>
void printDeque(const deque<T>& d) {for (const auto& elem : d) {cout << elem << " ";}cout << endl;
}int main() {// 1. 默认构造函数deque<int> d1;cout << "d1: ";printDeque(d1);  // 输出空// 2. 初始化列表deque<int> d2_1({9, 8, 8, 6, 5});cout << "d2_1: ";printDeque(d2_1);  // 9 8 8 6 5deque<int> d2_2 = {1, 8, 8, 8, 5};cout << "d2_2: ";printDeque(d2_2);  // 1 8 8 8 5// 3. 迭代器范围初始化deque<int> d3(d2_1.begin() + 1, d2_1.end() - 1);cout << "d3: ";printDeque(d3);  // 8 8 6// 4. 全0初始化（指定元素数量）deque<int> d4(10);cout << "d4: ";printDeque(d4);  // 0 0 0 0 0 0 0 0 0 0// 5. 固定值初始化（数量+值）deque<int> d5(8, 6);cout << "d5: ";printDeque(d5);  // 6 6 6 6 6 6 6 6// 6. 拷贝构造函数deque<int> d6(d5);cout << "d6: ";printDeque(d6);  // 6 6 6 6 6 6 6 6return 0;
}

deque 赋值操作

#include <iostream>
#include <deque>using namespace std;void printDeque(deque<int>& d) {for (deque<int>::iterator iter = d.begin(); iter != d.end(); iter++) {cout << *iter << " ";}cout << endl;
}int main() {deque<int> d = {9, 8, 5, 2, 1, 1};cout << "d: ";printDeque(d);// 1. = 赋值deque<int> d1;d1 = d;cout << "d1: ";printDeque(d1);// 2. assign(迭代器)deque<int> d2;d2.assign(d1.begin() + 1, d1.end());cout << "d2: ";printDeque(d2);// 3. 初始化列表deque<int> d3;d3.assign({1, 2, 3, 5, 6, 7});cout << "d3: ";printDeque(d3);// 4. 初始化 a 个 bdeque<int> d4;d4.assign(8, 6);cout << "d4: ";printDeque(d4);return 0;
}

deque 大小操作

#include <iostream>
#include <deque>using namespace std;// 用于打印双端队列元素的函数
void printDeque(deque<int>& d) {for (int i = 0; i < d.size(); ++i) {cout << d[i] << " ";}cout << endl;
}int main() {deque<int> d;// 检查初始状态下双端队列是否为空以及大小cout << "d.empty() = " << d.empty() << endl;cout << "d.size() = " << d.size() << endl;// 使用初始化列表为双端队列赋值d.assign({1, 2, 3});// 再次检查双端队列是否为空以及大小，并打印元素cout << "d.empty() = " << d.empty() << endl;cout << "d.size() = " << d.size() << endl;printDeque(d);// 将双端队列大小调整为18d.resize(18);cout << "d.size() = " << d.size() << endl;printDeque(d);// 将双端队列大小调整为20，新增元素值为6d.resize(20, 6);cout << "d.size() = " << d.size() << endl;printDeque(d);// 将双端队列大小调整为10000d.resize(10000);cout << "d.size() = " << d.size() << endl;printDeque(d);// 将双端队列大小调整为5d.resize(5);cout << "d.size() = " << d.size() << endl;printDeque(d);return 0;
}

结果

deque 数据插入

#include <iostream>
#include <deque>using namespace std;// 打印双端队列元素的函数
void printDeque(deque<int>& d) {for (deque<int>::iterator iter = d.begin(); iter != d.end(); iter++) {cout << *iter << " ";}cout << endl;
}int main() {deque<int> d;// 1. push_frontd.push_front(-1);d.push_front(-2);d.push_front(-3);// 此时双端队列d：-3 -2 -1printDeque(d); // 2. push_backd.push_back(1);d.push_back(2);d.push_back(3);// 此时双端队列d：-3 -2 -1 1 2 3printDeque(d); // 3. insert// 在迭代器指向位置前插入元素0，位置为d.begin() + 3，即原第4个元素前d.insert(d.begin() + 3, 0); // 此时双端队列d：-3 -2 -1 0 1 2 3printDeque(d); // 在迭代器指向位置前插入元素1，位置为d.end() - 1，即原倒数第2个元素前d.insert(d.end() - 1, 1); // 此时双端队列d：-3 -2 -1 0 1 2 1 3printDeque(d); // 在迭代器指向位置前插入[first, last)范围内的元素，first为d.begin() + 4 ，last为d.begin() + 6d.insert(d.begin() + 1, d.begin() + 4, d.begin() + 6); // 假设原双端队列d：-3 -2 -1 0 1 2 1 3  插入后：-3 1 2 -2 -1 0 1 2 1 3printDeque(d); return 0;
}

#include <iostream>
#include <deque>// 假设的打印函数，用于输出双端队列元素
void printDeque(const std::deque<int>& d) {for (int num : d) {std::cout << num << " ";}std::cout << std::endl;
}int main() {std::deque<int> d = {-1, 9, 8, 5, 5, 2, 1, 1, -1};printDeque(d);d.pop_back();printDeque(d);d.pop_front();printDeque(d);std::deque<int>::iterator it = d.erase(d.begin() + 2);// 9 8 2 1 1printDeque(d);std::cout << *it << std::endl;it = d.erase(it);// 9 8 1 1printDeque(d);std::cout << *it << std::endl;d.erase(d.begin() + 1, d.begin() + 3);printDeque(d);d.clear();printDeque(d);std::cout << "d.empty() = " << d.empty() << std::endl;std::cout << "d.size() = " << d.size() << std::endl;return 0;
}

deque 扩容机制.

deque的物理结构本质其实是指针数组每一个指针都指向一块连续的内存数据从头开始存入

当第一块内存存储满了之后想继续push_frort()时那么数据会存储在末尾当数据即将溢出时会继续扩容

底层原代码

deque 随机访问

#include <iostream>
#include <deque>
using namespace std;int main() {deque<int> d = { 9, 8, 7, 6, 5 };cout << d[2] << endl;cout << d.at(2) << endl;cout << d.front() << endl;cout << d.back() << endl;return 0;
}