重学C++系列之STL库

一、什么是STL库

        STL是“Standard Template Library”的缩写，中文翻译为“标准模板库”。C++STL是一套功能强大的C++模板类，提供了通用的模板类和函数，这些模板类和函数可以实现多种流行和常用的算法和数据结构，如字符串操作、链表、队列、栈。

        C++标准模板库的核心包括以下三个组件：

C++标准模板库组件

组件	描述
容器（顺序容器、关联容器）	容器是用来管理某一类对象的集合。C++提供了各种不同类型的容器，比如list, vector, map
算法	算法作用于容器，提供了执行各种操作的方式，包括对容器内容执行初始化、排序、搜索和转换等操作
迭代器	迭代器用于遍历对象集合的元素。类似于指针

二、STL的使用案例

        1、可以去看官网的操作文档，C++中文参考手册

        2、字符串模板类string

                加上头文件#include <string>

#include <iostream>
#include <string>
using namespace std;int main()
{// 1、定义string s1("hello");string s2 = "world";cout << "s1 = " << s1 << endl;cout << "s2 = " << s2 << endl;// 2、赋值string s3 = s1;string s4 = s1 + s2;string s5 = s1;s5 += s2;cout << "s3 = " << s3 << endl;cout << "s4 = " << s4 << endl;cout << "s5 = " << s5 << endl;// 3、at, 返回某个位置的引用string s6 = s1;s6.at(0) = 'p';cout << "s6 = " << s6 << endl;// 4、容量string s7 = s1;cout << "s7.size() = " << s7.size() << endl;cout << "s7.capacity() = " << s7.capacity() << endl;cout << "s7.length() = " << s7.length() << endl;string s8 = s1+s1+s1+s1+s1+s1;cout << "s8.capacity1() = " << s8.capacity() << endl;// 5、第一个字符和最后一个字符cout << "s1第一个字符" << s1.front() << endl;cout << "s1最后一个字符" << s1.back() << endl;// 6、返回字符串类中，字符串的指针地址const char* s_data = s1.data();const char* s_str = s1.c_str();cout << "s_data = " << s_data << endl;cout << "s_str = " << s_str << endl;// 7、插入string s9 = s1;s9.insert(0, "abcd");s9.insert(2, "xyz");cout << "s9 = " << s9 << endl;// 8、[]s1[0] = 'x';cout << "s1 = " << s1 << endl;// 9、追加string s10 = s1;s10.push_back('+');s10.append("xyz");cout << "s10 = " << s10 << endl;// 10、查找int index = s1.find("o");cout << "index = " << index << endl;// 11、比较string s12 = "hello";if(s12 == "hello"){cout << "s12 == hello" << endl;}// 12、迭代器string s13 = "hello world";cout << "s13 = ";for(string::iterator it = s13.begin(); it != s13.end(); it++){cout << *it;}cout << endl;// 13、数值转换string s14 = "123456";int value = stoi(s14);cout << "value = " << value << endl;string s15 = to_string(value);cout << "s15 = " << s15 << endl;// 14、 获取子串string s16 = s13.substr(0, 5);cout << "s16 = " << s16 << endl;return 0;
}

        3、顺序容器vector

                  加上头文件#include <vector>

#include <iostream>
#include <vector>
using namespace std;struct node 
{char *name;void func(){}
};int main()
{vector<int> myvector;// 1、插入myvector.push_back(10);myvector.push_back(20);myvector.push_back(30);myvector.push_back(40);myvector.push_back(50);// 2、迭代器遍历vector<int>::iterator it;for(it = myvector.begin(); it != myvector.end(); it++){cout << *it << '\t';}cout << endl;// 3、删除cout << "after del：" << endl;myvector.pop_back();myvector.pop_back();// 4、容量cout << "size = " << myvector.size() << endl;// 5、使用数组形式遍历for(int i = 0; i < myvector.size(); i++){cout << myvector.at(i) << '\t';}cout << endl;return 0;
}

        4、双向链表容器list

                 加上头文件#include <list>

#include <iostream>
#include <list>using namespace std;class Student
{
private:string name;int age;int score;
public:Student(string name = string(), int age = 18, int score = 30){this->age = age;this->name = name;this->score = score;}void show(){cout << name << '\t' << age << '\t' << score << endl;}friend bool cmp(const Student &s1, const Student &s2);string getName()const{return name;}void setAge(int Age){this->age = Age;}
};bool cmp(const Student &s1, const Student &s2)
{return s1.score > s2.score;
}int main()
{list<Student> mylist;// 插到后面，尾插mylist.push_back(*(new Student("zhang3", 20, 90)));mylist.push_back(*(new Student("zhang4", 21, 79)));// 插到前面，头插mylist.push_front(*(new Student("zhang7", 19, 89)));mylist.push_front(*(new Student("zhang8", 25, 80)));// 遍历，用迭代器cout << "before sort" << endl;list<Student>::iterator it;for(it = mylist.begin(); it != mylist.end(); it++){it->show();}// 排序mylist.sort(cmp);   // cmp函数是自定义的排序内容cout << "after sort" << endl;for(it = mylist.begin(); it != mylist.end(); it++){it->show();}// 删除it = mylist.begin();it = mylist.erase(it);cout << "after del first" << endl;for(it = mylist.begin(); it != mylist.end(); it++){it->show();}// 查找和修改for(it = mylist.begin(); it != mylist.end(); it++){if(it->getName() == "zhang7"){cout << "find zhang7" << endl;it->setAge(50);}}for(it = mylist.begin(); it != mylist.end(); it++){it->show();}return 0;
}

5、栈容器stack

#include <iostream>
#include <stack>using namespace std;int main()
{stack<int> mystack;// 入栈mystack.push(10);mystack.push(20);mystack.push(30);mystack.push(40);mystack.push(50);// 栈的元素个数cout << "size:" << mystack.size() << endl;// 栈没有空，就一直出栈int data;while(!mystack.empty()){data = mystack.top();   // 出栈前需要先获取栈顶元素mystack.pop();cout << data << "\t";}cout << endl;return 0;
}

6、队列容器queue

#include <iostream>
#include <queue>using namespace std;int main()
{queue<int> myqueue;// 入队myqueue.push(10);myqueue.push(20);myqueue.push(30);myqueue.push(40);myqueue.push(50);// 获取队列的元素个数 cout << "size: " << myqueue.size() << endl;// 队头元素cout << "front: " << myqueue.front() << endl;// 队尾元素cout << "back: " << myqueue.back() << endl;// 遍历int data;while(!myqueue.empty()){data = myqueue.front();myqueue.pop();  // 从队头出队的，先要保留队头元素cout << data << "\t";}cout << endl;return 0;
}

7、关联容器map 

#include <iostream>
#include <map>using namespace std;int main()
{// map是以键值对的方式存放数据// 第一个类型是键，第二类型是值，其中键不一定是整形可以是字符串map<int, string> mymap1;// 插入或者访问，键不一定要连续mymap1[1] = "a";mymap1[2] = "b";mymap1[10] = "c";mymap1[100] = "d";for(map<int, string>::iterator it = mymap1.begin(); it != mymap1.end(); it++){// 键用first来访问，值用second来访问// 不允许使用cout << it << endl; 来访问cout << it->first << " = " << it->second << endl;}// 不一定要连续map<string, string> mymap2;mymap2["zhang3"] = "123";mymap2["li4"] = "124";mymap2["wang5"] = "45";mymap2["hong6"] = "4543";for(map<string, string>::iterator it = mymap2.begin(); it != mymap2.end(); it++){// 键用first来访问，值用second来访问cout << it->first << " = " << it->second << endl;}return 0;
}

三、总结

        以上就是STL库中常用的容器以及对应的操作，使用时需要添加对应的头文件名，同时不同容器之间的有些相同操作是同名的，具体更多细节可以去看看官网的中文参考手册。