STL提供了一组表示容器、迭代器、函数对象和算法的模板。容器是一个与数组类似的单元，是同质的（既存储的值类型相同）；算法是完成特定任务的prescription;迭代器是用来遍历容器的对象；函数对象是类似于函数的对象，可以是类对象或者函数指针。

模板类vector

image.png

#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
using namespace std;
struct stu
{
    string title;
    int rating;
};

bool Fillstu(stu& s);
void Showstu(const stu& s);
bool operator<(const stu& s1,const stu& s2);
bool temp1(const stu& s1,const stu& s2);
int main()
{
    vector<stu> books;
    stu tempp;
    while(Fillstu(tempp))
        books.push_back(tempp);
        
    int num = books.size();
    cout<<"Book size: "<<books.size();
    vector<stu> books2(books);
    cout<<"Rating\tbooks\n";
    for(int i=0;i<num;i++)
    {
        cout<<books[i].rating<<"\t"<<books[i].title<<endl;
    }
    vector<stu>::iterator st;                //迭代器 
    cout<<"Using iterator:\n" ;
    cout<<"Rating\tbooks\n";
    for(st=books.begin();st!=books.end();st++)
    {
        Showstu(*st) ;
    }
    books.erase(books.begin()+1,books.begin()+3);
    cout<<"After erasing\n";
    for_each(books.begin(),books.end(),Showstu);

    books.insert(books.begin(),books2.begin(),books2.begin()+2);
    cout<<"After inserting\n";
    cout<<"Rating\tbooks\n";
    for_each(books.begin(),books.end(),Showstu); 
    
    
    books.swap(books2);
    cout<<"After swapping\n";
    cout<<"Rating\tbooks\n";
    for(auto x:books) Showstu(x);
    
    sort(books.begin(),books.end());
    cout<<"Aftering sort with 2 parameter\n";
    cout<<"Rating\tbooks\n";
    for(auto x:books) Showstu(x);

    random_shuffle(books.begin(),books.end()) ;
    cout<<"After random shuffle:\n";
    cout<<"Rating\tbooks\n";
    for(auto x:books) Showstu(x);
    
    sort(books.begin(),books.end(),temp1);
    cout<<"Aftering sort with 3 parameter\n";
    cout<<"Rating\tbooks\n";
    for(auto x:books) Showstu(x);
    
}

bool operator<(const stu& s1,const stu& s2)
{
    if(s1.title<s2.title)
        return true;
    else if(s1.title == s2.title && s1.title<s2.title )
        return true;
    else
        return false;
}

bool Fillstu(stu& s)
{
    cout<<"Enter book title(quit to quit): ";
    getline(cin,s.title);
    if(s.title =="quit")
        return false;
    cout<<"Enter book rating: ";
    cin>>s.rating;
    if(!cin)
        return false;
    while(cin.get()!='\n')
        continue;
    return true;
}

void Showstu(const stu& s)
{
    cout<<s.rating<<"\t"<<s.title<<endl;
}

bool temp1(const stu& s1,const stu& s2)
{
    if(s1.rating<s2.rating)
        return true;
    else
        return false;
}

1. for_each() 和 random_shuffle()函数在头文件algorithm中
2. 2个参数的sort()函数需要有定义operator<（）函数来比较相关的元素。
3. 3个参数的sort()函数需要定义一个比较相关元素的函数

image.png

image.png