cpp学习笔记：STL deque容器
一、deque与vector的区别
①vector对于头部的插入删除数据低，数据量越大，效率越低。
②deque相对而言，对头部的插入删除速度比vector快。
③vector访问元素时的速度会比deque快，和两者内部实现有关。
二、deque构造函数
deque
d1; //构造d1 deque
d2(d1.begin(),d1.end()); //把d1开始到结尾构造给d2 deque
d3(10,100); //将10个100放入d3 deque
d4=d3; //将d3赋值给d4
#include
#include void printDeque(const deque& d)
{for (deque::const_iterator it = d.begin(); it != d.end();it++){cout << *it << " ";}cout << endl;
}void text01()
{deque d1;for (int i = 0; i < 10;i++){d1.push_back(i);}printDeque(d1);deque d2(d1.begin(), d1.end());printDeque(d2);deque d3(10, 100);printDeque(d3);deque d4 = d3;printDeque(d4);
} 三、deque赋值操作
deque
d2; d2 = d1; deque
d3; d3.assign(d1.begin(), d1.end()); deque
d4; d4.assign(10, 100);
#include
#include void printDeque(const deque& d)
{for (deque::const_iterator it = d.begin(); it != d.end();it++){cout << *it << " ";}cout << endl;
}void text01()
{deque d1;for (int i = 0; i < 10;i++){d1.push_back(i);}printDeque(d1);deque d2;d2 = d1;printDeque(d2);deque d3;d3.assign(d1.begin(), d1.end());printDeque(d3);
} 四、deque大小操作
empty() //判断容器是否为空，返回值=1时为空
capacity() //容器的容量
size() //返回容器中元素的个数
resize(int num) //重新指定容器的长度为num，
//若容器边长，则默认值填充，变短则超出部分被删除
resize(int num,elem) //重新指定容器的长度为num，
//若容器边长，则以elem值填充新位置，若变短，则末尾超出位置被删除
总结：
判断元素是否为空：empty 返回元素的个数：size
返回容器容量：capacity 重新指定大小：resize
void text01()
{deque d1;for (int i = 0; i < 10; i++){d1.push_back(i);} printDeque(d1);if (d1.empty()) {cout << "d1为空!" << endl;} else {cout << "d1不为空!" << endl;cout << "d1的大小为：" << d1.size() << endl;} d1.resize(15, 1);printDeque(d1);d1.resize(5);printDeque(d1);
}
五、deque插入和删除
deque
d; d.push_back(10); //尾插
d.push_front(10); //头插
d.pop_back(); //尾删
d.pop_front(); //头删
d.insert(d.begin(), 2, 10000); //在开头插入两个10000
d2.insert(d.begin(), d2.begin(), d2.end());
d.erase(d.begin()); //删除第一个
d.erase(d.begin(), d.end()); //删除所有
d.clear();
总结：
尾插：push_back 尾删：pop_back
头插：push_front 头删：pop_front
void text01()
{deque d;d.push_back(10); //尾插d.push_back(20);d.push_front(10); //头插d.push_front(20);printDeque(d);d.pop_back(); //尾删d.pop_front(); //头删printDeque(d);
}void text02()
{deque d;d.push_back(10);d.push_back(20);d.push_front(100);d.push_front(200);printDeque(d);d.insert(d.begin(), 2, 10000);printDeque(d);d.insert(d.begin(), 2, 1000);printDeque(d);deque d2;d2.push_back(1);d2.push_back(2);d2.push_back(3);d2.insert(d.begin(), d2.begin(), d2.end());printDeque(d);
}void text03()
{deque d;d.push_back(10);d.push_back(20);d.push_front(100);d.push_front(200);printDeque(d);d.erase(d.begin());printDeque(d);d.clear();printDeque(d);
}
六、deque数据存取
at(int idx); //返回索引idx所指的数据
operator [ ]; //返回索引idx所指的数据
front(); //返回容器中第一个数据元素
back(); //返回容器中最后一个数据元素
void text01()
{deque d;d.push_back(10); //尾插d.push_back(20);d.push_front(100);d.push_front(200);for (int i = 0; i < d.size();i++){cout << d[i] << " ";}cout << endl;for (int i = 0; i < d.size();i++){cout << d.at(i) << " ";}cout << endl;cout << d.front() << endl;cout << d.back() << endl;
} 七、deque排序
sort(d.begin(), d.end()); //排序
void text01()
{deque d;d.push_back(10); //尾插d.push_back(20);d.push_front(100);d.push_front(200);printDeque(d);sort(d.begin(), d.end());printDeque(d);
} 八、案例：评委打分
#include
#include
#include
#include class Person
{
public:Person(string name,int score){this->m_Name = name;this->m_Score = score;}string m_Name;int m_Score;
};void createPerson(vector&v)
{string nameSeed = "ABCDE";for (int i = 0; i < 5;i++){string name = "选手";name += nameSeed[i];int score = 0;Person p(name, score);v.push_back(p);}
}void SetScore(vector&v)
{for (vector::iterator it = v.begin(); it != v.end();it++){deque d;for (int i = 0; i < 10;i++){int score = rand() % 41 + 60;d.push_back(score);}//排序sort(d.begin(), d.end());//去掉最高分和最低分d.pop_back();d.pop_front();int sum = 0;for (deque::iterator dit = d.begin(); dit != d.end();dit++){sum += *dit;}int avg = sum / d.size();it->m_Score = avg;}
}void showScore(vector&v)
{for (vector::iterator it = v.begin(); it != v.end();it++){cout << "姓名：" << it->m_Name << " 平均分：" << it->m_Score << endl;}
}int main()
{srand((unsigned int)time(NULL));vector v;createPerson(v);SetScore(v);showScore(v);system("pause");return 0;
}