STL之list

标签：list   splice   advance   iterator   

list中的函数代码事例如下：

#include <iostream>
#include <list>

using namespace std;
typedef list<int> INTLIST;

//从前向后显示list队列的全部元素
void put_list(INTLIST list, char *name)
{
    INTLIST::iterator plist;

    cout << "The contents of " << name << " : ";
    for(plist = list.begin(); plist != list.end(); plist++)
        cout << *plist << " ";
    cout<<endl;
}

//测试list容器的功能
int main(){
//list1对象初始为空
    INTLIST list1;   
    //list2对象最初有10个值为6的元素 
    INTLIST list2(10,6); 
    //list3对象最初有9个值为6的元素 
    INTLIST list3(list2.begin(),--list2.end()); 

    //声明一个名为i的双向迭代器
    INTLIST::iterator i;

    //从前向后显示各list对象的元素
    put_list(list1,"list1");
    put_list(list2,"list2");
    put_list(list3,"list3");
    
//从list1序列后面添加两个元素
list1.push_back(2);
list1.push_back(4);
cout<<"list1.push_back(2) and list1.push_back(4):"<<endl;
    put_list(list1,"list1");

//从list1序列前面添加两个元素
list1.push_front(5);
list1.push_front(7);
cout<<"list1.push_front(5) and list1.push_front(7):"<<endl;
    put_list(list1,"list1");

//在list1序列中间插入数据3个9 
list1.insert(++list1.begin(),3,9);
cout<<"list1.insert(++list1.begin(),3,9):"<<endl;
    put_list(list1,"list1");

//测试引用类函数
cout<<"list1.front()="<<list1.front()<<endl;
cout<<"list1.back()="<<list1.back()<<endl;

//从list1序列的前后各移去一个元素
list1.pop_front();
list1.pop_back();
cout<<"list1.pop_front() and list1.pop_back():"<<endl;
    put_list(list1,"list1");

//清除list1中的第2个元素
list1.erase(++list1.begin());
cout<<"list1.erase(++list1.begin()):"<<endl;
    put_list(list1,"list1");

//对list2赋值并显示
list2.assign(8,1);
cout<<"list2.assign(8,1):"<<endl;
    put_list(list2,"list2");

//显示序列的状态信息
cout<<"list1.max_size(): "<<list1.max_size()<<endl;
cout<<"list1.size(): "<<list1.size()<<endl;
cout<<"list1.empty(): "<<list1.empty()<<endl;

//list序列容器的运算
    put_list(list1,"list1");
    put_list(list3,"list3");
cout<<"list1>list3: "<<(list1>list3)<<endl;
cout<<"list1<list3: "<<(list1<list3)<<endl;

//对list1容器排序
list1.sort();
cout<<"list1.sort(): "<<endl;
    put_list(list1,"list1");
    
//结合处理
list1.splice(++list1.begin(), list3);
cout<<"list1.splice(++list1.begin(), list3)"<<endl;
    put_list(list1,"list1");
    put_list(list3,"list3"); 
cout<<"list3.max_size(): "<<list3.max_size()<<endl;
cout<<"list3.size(): "<<list3.size()<<endl;
cout<<"list3.empty(): "<<list3.empty()<<endl;
}

The splice() function inserts lst at location pos. If specified, the element(s) at del or from start to end are removed.

splice() simply moves elements from one list to another, and doesn‘t actually do any copying or deleting. Because of this, splice() runs in constant time.

看个例子：

#include <iostream>
#include <list>
 
std::ostream& operator<<(std::ostream& ostr, const std::list<int>& list)
{
    for (auto &i : list) {
        ostr << " " << i;
    }
    return ostr;
}
 
int main ()
{
    std::list<int> list1 = { 1, 2, 3, 4, 5 };
    std::list<int> list2 = { 10, 20, 30, 40, 50 };
 
    auto it = list1.begin();
    std::advance(it, 2);
 
    list1.splice(it, list2);
 
    std::cout << "list1: " << list1 << "\n";
    std::cout << "list2: " << list2 << "\n";
 
    list2.splice(list2.begin(), list1, it, list1.end());
 
    std::cout << "list1: " << list1 << "\n";
    std::cout << "list2: " << list2 << "\n";
}

list1:  1 2 10 20 30 40 50 3 4 5
list2: 
list1:  1 2 10 20 30 40 50
list2:  3 4 5

其中it代表的位置始终是3的位置，当3的位置变的时候，it也跟着变了，而不是简单的常数，所以我们可以看到iterator跟指针的用法是类似的，可以理解为指针。

这段代码还用到了函数advance()，其用法为：

template< class InputIt, class Distance >
void advance( InputIt& it, Distance n );

#include <iostream>
#include <iterator>
#include <vector>
 
int main() 
{
    std::vector<int> v{ 3, 1, 4 };
 
    auto vi = v.begin();
 
    std::advance(vi, 2);
 
    std::cout << *vi << '\n';
}

STL之list

标签：list   splice   advance   iterator   

原文地址：http://blog.csdn.net/puppylpg/article/details/46575257