STL list

std::list 的特点

链表的结构包括：数据域，前驱指针，后继指针。list类的STL实现允许在开头、末尾、中间插入元素，需要的时间固定。

要是用std::stl类，需要包含头文件<list>:

#include <list>

基本的list操作

实例化std::list对象

#include <list>
#include <vector>
#include <iostream>
using namespace std;

template <typename T>
void DisplayContents (const T& container)
{
	for (list<int>::const_iterator element = container.begin();//声明一个指向list元素的迭代器
        element != container.end();
        ++ element )
       cout << *element << ' ';

   cout << endl;
}
int main ()
{
   //using namespace std;

   // instantiate an empty list
   list <int> listIntegers;

   // instantiate a list with 10 integers
   list<int> listWith10Integers(10);

   // instantiate a list with 4 integers, each initialized to 99
   list<int> listWith4IntegerEach99 (4, 99);

   // create an exact copy of an existing list
   list<int> listCopyAnother(listWith4IntegerEach99);

   // a vector with 10 integers, each 2017
   vector<int> vecIntegers(10, 2017);

   // instantiate a list using values from another container
   list<int> listContainsCopyOfAnother(vecIntegers.begin(),
                                       vecIntegers.end());
    DisplayContents(listWith4IntegerEach99);
   return 0;
}

在list开头或末尾插入元素

#include <list>
#include <iostream>
using namespace std;
// for non-C++11 compliant compilers
template <typename T>
void DisplayContents (const T& Input)
{
   for (typename T::const_iterator iElement = Input.begin ()
       ; iElement != Input.end ()
       ; ++ iElement )
       cout << *iElement << ' ';

   cout << endl;
}
/*
支持C++11的编译器可以用这个
template <typename T>
void DisplayContents (const T& container)
{
	for (auto element = container.cbegin();
        element != container.cend();
        ++ element )
       cout << *element << ' ';

   cout << endl;
}
*/
int main ()
{
    std::list <int> linkInts;
   linkInts.push_back (-101);
   linkInts.push_back (42);
   linkInts.push_front (10);
   linkInts.push_front (2011);
   linkInts.push_back (-1);
   linkInts.push_back (9999);

   DisplayContents(linkInts);

   return 0;
}

运行结果

我的编译器，不支持C++11，不能使用列表初始化的方法来个对象初值。

在list中插入元素

#include <list>
#include <iostream>
using namespace std;

template <typename T>
void DisplayContents (const T& container)
{
	for (typename T :: const_iterator element = container.begin();//这种方式一定要用const_iterator类型吗？
         element != container.end();
         ++ element )
       cout << *element << ' ';

   cout << endl;
}

int main ()
{
   list <int> linkInts1;

   // Inserting elements at the beginning...
   linkInts1.insert (linkInts1.begin (), 2);
   linkInts1.insert (linkInts1.begin (), 1);

   // Inserting an element at the end...
   linkInts1.insert (linkInts1.end (), 3);

   cout << "The contents of list 1 after inserting elements:" << endl;
   DisplayContents (linkInts1);

   list <int> linkInts2;

   // Inserting 4 elements of the same value 0...
   linkInts2.insert (linkInts2.begin (), 4, 0);

   cout << "The contents of list 2 after inserting '";
   cout << linkInts2.size () << "' elements of a value:" << endl;
   DisplayContents (linkInts2);

   list <int> linkInts3;

   // Inserting elements from another list at the beginning...
   linkInts3.insert (linkInts3.begin (),
                    linkInts1.begin (), linkInts1.end ());

   cout << "The contents of list 3 after inserting the contents of ";
   cout << "list 1 at the beginning:" << endl;
   DisplayContents (linkInts3);

   // Inserting elements from another list at the end...
   linkInts3.insert (linkInts3.end (),
                  linkInts2.begin (), linkInts2.end ());

   cout << "The contents of list 3 after inserting ";
   cout << "the contents of list 2 at the end:" << endl;
   DisplayContents (linkInts3);

   return 0;
}

运行结果

删除list中的元素

#include <iostream>
using namespace std;

template <typename T>
void DisplayContents(const T& container)
{
   for(typename T:: const_iterator element = container.begin();
       element != container.end();
       ++ element )
     cout << *element << ' ';

   cout << endl;
}

int main()
{
	std::list <int> linkInts;
	linkInts.push_back(4);
    linkInts.push_back(3);
	linkInts.push_back(5);
	linkInts.push_back(-1);
	linkInts.push_back(2017);


   // Store an iterator obtained in using insert()
   //查找函数返回的也是一个迭代器，该迭代器指向新插入的元素
   list<int>::iterator iValue2 = linkInts.insert(linkInts.begin(), 2);//声明一个指向list元素的迭代器

   cout << "Initial contents of the list:" << endl;
   DisplayContents(linkInts);

   cout << "After erasing element '"<< *iValue2 << "':" << endl;
   linkInts.erase(iValue2);//此时迭代器指向的是list头部的元素“2”
   DisplayContents(linkInts);

   linkInts.erase(linkInts.begin(), linkInts.end());//可以删除两个迭代器之间的所有元素
   cout << "Number of elements after erasing range: ";
   cout << linkInts.size() << endl;//求元素的大小

   linkInts.clear();

   return 0;
}

运行结果

对list中的元素进行反转和排序

使用list::reverse()反转元素的排列顺序

#include <list>
#include <iostream>
using namespace std;

template <typename T>
void DisplayContents(const T& container)
{
	for (typename T::const_iterator element = container.begin();
         element != container.end();
         ++ element )
     cout << *element << ' ';

   cout << endl;
}

int main()
{
   std::list <int> linkInts;
   linkInts.push_back(0);
   linkInts.push_back(1);
   linkInts.push_back(2);
   linkInts.push_back(3);
   linkInts.push_back(4);
   linkInts.push_back(5);


   cout << "Initial contents of the list:" << endl;
   DisplayContents(linkInts);

   linkInts.reverse();

   cout << "Contents of the list after using reverse():" << endl;
   DisplayContents(linkInts);

   return 0;
}

运行结果

reverse()只是反转list中元素的排列顺序。它是一个没有参数的简单函数，确保指向元素的迭代器在反转后仍有效——如果程序员保存了该迭代器。

对元素进行排序

#include <list>
#include <iostream>
using namespace std;

bool SortPredicate_Descending (const int& lsh, const int& rsh) //二元谓词函数
{
   // define criteria for list::sort: return true for desired order
   return (lsh > rsh);
}

template <typename T>
void DisplayContents (const T& container)
{
   for (list<int>::const_iterator element = container.begin();
        element != container.end();
        ++ element )
      cout << *element << ' ';

   cout << endl;
}

int main ()
{
   list <int> linkInts;
   linkInts.push_back(0);
   linkInts.push_back(-1);
   linkInts.push_back(2011);
   linkInts.push_back(444);
   linkInts.push_back(-5);
   cout << "Initial contents of the list are - " << endl;
   DisplayContents (linkInts);

   linkInts.sort ();

   cout << "Order after sort():" << endl;
   DisplayContents (linkInts);

   linkInts.sort (SortPredicate_Descending);
   cout << "Order after sort() with a predicate:" << endl;
   DisplayContents (linkInts);

   return 0;
}

运行结果

list默认的排序是升序的，可用二元谓语动词来设置排序的规则。

对包含对象的list进行排序以及删除其中的元素

#include <list>
#include <string>
#include <iostream>
using namespace std;
//这是一个循环输出的函数
template <typename T>
void displayAsContents (const T& container)
{
   for (typename T::const_iterator element = container.begin();
         element != container.end();
         ++ element )
     cout << *element << endl;

   cout << endl;
}
//定义了一个结构体（也属于类类型）
struct ContactItem
{
   string name;
   string phone;
   string displayAs;
   //结构体的构造函数
   ContactItem (const string& conName, const string & conNum)
   {
      name = conName;
      phone = conNum;
      displayAs = (name + ": " + phone);
   }

   // used by list::remove() given contact list item
   bool operator == (const ContactItem& itemToCompare) const
   {
      return (itemToCompare.name == this->name);
   }

   // used by list::sort() without parameters
   bool operator < (const ContactItem& itemToCompare) const
   {
      return (this->name < itemToCompare.name);
   }

   // Used in displayAsContents via cout
   operator const char*() const
   {
     return displayAs.c_str();
   }
};

bool SortOnphoneNumber (const ContactItem& item1,
                           const ContactItem& item2)
{
   return (item1.phone < item2.phone);
}

int main ()
{
   list <ContactItem> contacts;
   contacts.push_back(ContactItem("Jack Welsch", "+1 7889879879"));
   contacts.push_back(ContactItem("Bill Gates", "+1 97 789787998"));
   contacts.push_back(ContactItem("Angi Merkel", "+49 234565466"));
   contacts.push_back(ContactItem("Vlad Putin", "+7 66454564797"));
   contacts.push_back(ContactItem("Ben Affleck", "+1 745641314"));
   contacts.push_back(ContactItem("Dan Craig", "+44 123641976"));

   cout << "List in initial order: " << endl;
   displayAsContents(contacts);

   contacts.sort();
   cout << "Sorting in alphabetical order via operator<:" << endl;
   displayAsContents(contacts);

   contacts.sort(SortOnphoneNumber);
   cout << "Sorting in order of phone numbers via predicate:" << endl;
   displayAsContents(contacts);

   cout << "After erasing Putin from the list: " << endl;
   contacts.remove(ContactItem("Vlad Putin", ""));//这里能够用得上结构体重载的“==”吗？
   displayAsContents(contacts);

   return 0;
}

运行结果

remove()和sort()都是有对应的谓词函数的，如果容器中装的是类的对象，则需要在相应的类中重载“==”和“<”号。