C++ list用法

创建一个list实例并赋值：

// 创建实例以及赋值
#include <iostream>
#include <list>
using namespace std;
int main () {
    //第一种，通过构造函数
    int myints[] = {75,23,65,42,13};
    list<int> mylist1(myints, myints+5);
    list<int> mylist2(2,100);         // 2个值为100的元素
    //第二种，用push_back，或push_front
    for (int i = 1; i <= 5; ++i) mylist1.push_back(i);
    mylist2.push_front (200);
    mylist2.push_front (300);
    //第三种,用assign
    list<int> first;
    list<int> second;
    first.assign(7,100);                       // 给first添加7个值为100的元素
    second.assign(first.begin(), first.end()); // 复制first给second
    int myints[] = {16, 8, 4};
    first.assign (myints, myints + 3);         // 将数组myints的内容添加给first

    //第四种，见insert函数
    return 0;
}

成员函数：

Iterator:  （可用于遍历list）

iterator begin();  //返回指向第一个元素的迭代器

iterator end();  //返回指向最后一个元素的迭代器

reverse_iterator rbegin();  //返回指向第一个元素的逆向迭代器

reverse_rend();  //返回指向最后一个元素的逆向迭代器

//list的遍历
#include <iostream>
#include <list>
using namespace std;
int main () {
    int myints[] = {75,23,65,42,13};
    list<int> mylist (myints,myints+5);
    cout << "mylist contains:";
    //这是正序输出：
    for (list<int>::iterator it = mylist.begin(); it != mylist.end(); ++it)
        cout << ' ' << *it;
    cout << '
';

    list.clear();
    //逆序输出：
    for (int i = 1; i <= 5; ++i) mylist.push_back(i);
    cout << "mylist backwards:";
    for (list<int>::reverse_iterator rit = mylist.rbegin(); rit != mylist.rend(); ++rit)
        cout << ' ' << *rit;
    cout << '
';
    return 0;
}

输出结果为：
mylist contains: 75 23 65 42 13
mylist backwards: 5 4 3 2 1

Capacity: （用于获取list容器大小信息）

bool empty() const;  //list为空时返回true

size_type size() const;  //返回list容器里元素的个数

size_type max_size() const;  //返回list容器最大能容纳的元素的个数，主要用于调用list的resize()函数时，检查所请求的size大小是否被允许

Element access:（用于获取首尾元素）

reference front();  //返回第一个元素的引用

const_reference front() const;

reference back();  //返回最后一个元素的引用

const_reference front() const;

Modifiers:

• asign  //给容器添加新内容：

template<class InputIterator>

void assign(InputIterator first, InputIterator last);  //first,last是一个序列中起始和结束的迭代器的值，[first, last)包含了序列中所有元素

void assign(size_type n, const value_type& val);  //给list赋值n个值为val的元素

// list::assign
#include <iostream>
#include <list>
using namespace std;
int main () {
    list<int> first;
    list<int> second;
    first.assign(7,100);                      // 给first添加7个值为100的元素
    second.assign(first.begin(), first.end()); // 复制first给second

    int myints[] = {16, 8, 4};
    first.assign (myints, myints + 3);            // 将数组myints的内容添加给first

    cout << "Size of first: " << int (first.size()) << '
';
    cout << "Size of second: " << int (second.size()) << '
';
    return 0;
}
输出结果为：
Size of first: 3
Size of second: 7

• push_front, pop_front, push_back, pop_back

void push_front(const value_type& val);  //在list头添加元素

void pop_front();  //删除list头的元素

void push_back(const value_type& val);  //在list尾添加元素

void pop_back();  //删除list尾的元素

#include <iostream>
#include <list>
using namespace std;
int main () {
    list<int> mylist (2,100);         // 2个值为100的元素
    // list::push_front
    mylist.push_front (200);
    mylist.push_front (300);

    cout << "mylist contains:";
    for (list<int>::iterator it = mylist.begin(); it != mylist.end(); ++it)
        cout << ' ' << *it;
    cout << '
';

    // list::pop_front
    cout << "Popping out the elements in mylist:";
    while (!mylist.empty()) {
        cout << ' ' << mylist.front();
        mylist.pop_front();
    }
    cout << "
Final size of mylist is " << mylist.size() << '
';

    // list::push_back
    int myint;
    cout << "Please enter some integers (enter 0 to end):
";
    do {
        cin >> myint;
        mylist.push_back (myint);
    } while (myint);
    cout << "mylist contains:";
    for (list<int>::iterator it = mylist.begin(); it != mylist.end(); ++it)
        cout << ' ' << *it;
    cout << '
';

    // list::pop_back
    while (!mylist.empty()) {
        cout << ' ' <<  mylist.back();
        mylist.pop_back();
    }
    cout << "
Final size of mylist is " << mylist.size() << '
';

    return 0;
}
输出结果：
mylist contai: 300 200 100 100
Popping out the elements in mylist: 300 200 100 100
Final size of mylist is 0
Please enter some integers (enter 0 to end):
56 23 8 5 6 0
mylist contains: 56 23 8 5 6 0
 0 6 5 8 23 56
Final size of mylist is 0

• insert  //插入元素：

iterator insert (iterator position, const value_type& val);  //position是要插入的这个list的迭代器，val是要插入的值

void insert (iterator position, size_type n, const value_type& val);  //从该list容器中的position位置处开始，插入n个值为val的元素

template <class InputIterator>

void insert (iterator position, InputIterator first, InputIterator last);  //first，last是我们选择的把值插入到这个list中的值所在的容器的迭代器

// inserting into a list
#include <iostream>
#include <list>
#include <vector>
using namespace std;
int main () {
    list<int> mylist;
    list<int>::iterator it;
    // 初始化
    for (int i = 1; i <= 5; ++i) mylist.push_back(i); // 1 2 3 4 5
    it = mylist.begin();
    ++it;       // 迭代器it现在指向数字2                      ^
    //在i0t指向的位置出插入元素10
    mylist.insert (it,10);                        // 1 10 2 3 4 5

    // "it" 仍然指向数字2                                   ^
    //在it指向的位置出插入两个元素20
    mylist.insert (it,2,20);                      // 1 10 20 20 2 3 4 5

    --it;       // 现在it指向数字20                             ^

    vector<int> myvector (2,30); //创建vector容器，并初始化为含有2个值为30的元素
    //将vector容器的值插入list中
    mylist.insert (it,myvector.begin(),myvector.end());
                                                // 1 10 20 30 30 20 2 3 4 5
    //it仍然指向数字20                            //               ^
    cout << "mylist contains:";
    for (it = mylist.begin(); it != mylist.end(); ++it)
        cout << ' ' << *it;
    cout << '
';

    return 0;
}
输出结果：
mylist contains: 1 10 20 30 30 20 2 3 4 5

• erase  //删除元素：

iterator erase (iterator position);  //删除迭代器position指向的值，也可以不用变量接收其返回值

iterator erase (iterator first, iterator last);  //删除[first, last)中的值，也可以不用变量接收其返回值

// erasing from list
#include <iostream>
#include <list>
using namespace std;
int main () {
    list<int> mylist;
    list<int>::iterator it1,it2;

    // set some values:
    for (int i = 1; i < 10; ++i) mylist.push_back(i*10);

                                // 10 20 30 40 50 60 70 80 90
    it1 = it2 = mylist.begin(); // ^^
    advance (it2,6);            // ^                 ^
    ++it1;                      //    ^              ^

    it1 = mylist.erase (it1);   // 10 30 40 50 60 70 80 90
                                //    ^           ^

    it2 = mylist.erase (it2);   // 10 30 40 50 60 80 90
                                //    ^           ^

    ++it1;                      //       ^        ^
    --it2;                      //       ^     ^
    //没有变量接收其返回值
    mylist.erase (it1,it2);     // 10 30 60 80 90
                                //       ^
    cout << "*it1 : " << *it1 << endl;
    cout << "mylist contains:";
    for (it1 = mylist.begin(); it1 != mylist.end(); ++it1)
        cout << ' ' << *it1;
    cout << '
';

  return 0;
}
输出结果：
it1 : 40
mylist contains: 10 30 60 80 90

• swap  //交换两个list的内容

void swap(list& x);  //要交换的两个列表的存储的元素的类型必须是一样的，列表大小可以不同

// swap lists
#include <iostream>
#include <list>
using namespace std;
int main () {
    list<int> first (3,100);   // 三个值为100的元素
    list<int> second (5,200);  // 五个值为200的元素

    first.swap(second);

    cout << "first contains:";
    for (list<int>::iterator it = first.begin(); it != first.end(); it++)
        cout << ' ' << *it;
    cout << '
';

    cout << "second contains:";
    for (list<int>::iterator it = second.begin(); it != second.end(); it++)
        cout << ' ' << *it;
    cout << '
';

    return 0;
}
输出结果：
first contains: 200 200 200 200 200
second contains: 100 100 100

• resize  //调整list大小

void resize (size_type n, value_type val = value_type());  //将list大小调整为能容纳n个元素，若n大于当前list大小，则会从list末尾一直插入val值，直到list大小满足n;

// resizing list
#include <iostream>
#include <list>
using namespace std;
int main () {
    list<int> mylist;

    // 初始化
    for (int i = 1; i < 10; ++i) mylist.push_back(i);

    mylist.resize(5);
    mylist.resize(8,100);
    mylist.resize(12);

    cout << "mylist contains:";
    for (list<int>::iterator it = mylist.begin(); it != mylist.end(); ++it)
        cout << ' ' << *it;
    cout << '
';

  return 0;
}
输出结果：
mylist contains: 1 2 3 4 5 100 100 100 0 0 0 0

• clear  //清空list

void clear();  //删除list的所有元素

// clearing lists
#include <iostream>
#include <list>
using namespace std;
int main () {
    list<int> mylist;
    list<int>::iterator it;

    mylist.push_back (100);
    mylist.push_back (200);
    mylist.push_back (300);

    cout << "mylist contains:";
    for (it = mylist.begin(); it != mylist.end(); ++it)
        cout << ' ' << *it;
    cout << '
';

    mylist.clear();
    mylist.push_back (1101);
    mylist.push_back (2202);

    cout << "mylist contains:";
    for (it = mylist.begin(); it != mylist.end(); ++it)
        cout << ' ' << *it;
    cout << '
';

  return 0;
}
输出结果：
mylist contains: 100 200 300
mylist contains: 1101 2202

Operations:

• splice  //将一个list中的值移到另一个list中

void splice (iterator position, list& x);  //将列表x中的所有元素移到当前list中，从当前列表的position指向的位置开始，此时列表x为空

void splice (iterator position, list& x, iterator i);  //将列表x中迭代器 i 指向的元素移到当前list的position指向的位置处，由于i指向的元素从列表x中被移除，所以迭代器 i 此时是invalid的；position是当前列表的迭代器，i是列表x的迭代器

void splice (iterator position, list& x, iterator first, iterator last);  //将列表x中[first, last)的元素移到当前list中，从position指向的位置开始；first, last是列表x的迭代器

// splicing lists
#include <iostream>
#include <list>
using namespace std;
int main () {
    list<int> mylist1, mylist2;
    list<int>::iterator it;

    // 初始化
    for (int i = 1; i <= 4; ++i)
       mylist1.push_back(i);      // mylist1: 1 2 3 4

    for (int i = 1; i <= 3; ++i)
       mylist2.push_back(i*10);   // mylist2: 10 20 30

    it = mylist1.begin();
    ++it;                         // 指向数字2

    mylist1.splice (it, mylist2); // mylist1: 1 10 20 30 2 3 4
                                  // mylist2 (empty)
                                  // "it" 仍然指向数字2

    mylist2.splice (mylist2.begin(),mylist1, it);
                                // mylist1: 1 10 20 30 3 4
                                // mylist2: 2
                                // "it" 此时已经无效了
    it = mylist1.begin();
    advance(it,3);           // "it" 指向数字30

    mylist1.splice ( mylist1.begin(), mylist1, it, mylist1.end());
                                // mylist1: 30 3 4 1 10 20

    cout << "mylist1 contains:";
    for (it = mylist1.begin(); it != mylist1.end(); ++it)
        cout << ' ' << *it;
    cout << '
';

    cout << "mylist2 contains:";
    for (it = mylist2.begin(); it != mylist2.end(); ++it)
        cout << ' ' << *it;
    cout << '
';

  return 0;
}
输出结果：
mylist1 contains: 30 3 4 1 10 20
mylist2 contains: 2

• remove  //删除list中特定的值

void remove (const value_type& val);  //从list中删除所有值为val的元素

// remove from list
#include <iostream>
#include <list>
using namespace std;
int main () {
    int myints[]= {17, 89, 7, 89, 14};
    list<int> mylist (myints,myints+5);

    mylist.remove(89);

    cout << "mylist contains:";
    for (list<int>::iterator it = mylist.begin(); it != mylist.end(); ++it)
        cout << ' ' << *it;
    cout << '
';

    return 0;
}
输出结果：
mylist contains: 17 7 14

• remove_if  //按条件删除

template <class Predicate>

void remove_if (Predicate pred)；  //pred可以是一个函数，也可以是一个class，但它需要有一个参数，且参数类型跟list中存储元素类型相同，满足条件就返回true

// list::remove_if
#include <iostream>
#include <list>
using namespace std;
// a predicate implemented as a function:
bool single_digit (const int& value) { return (value < 10); }

// a predicate implemented as a class:
struct is_odd {
  //重载操作符 ()
  bool operator() (const int& value) { return (value % 2) == 1; }
};

int main () {
    int myints[] = {15, 36, 7, 17, 20, 39, 4, 1};
    list<int> mylist (myints, myints + 8);   // 15 36 7 17 20 39 4 1

    mylist.remove_if (single_digit);           // 15 36 17 20 39

    mylist.remove_if (is_odd());               // 36 20

    cout << "mylist contains:";
    for (std::list<int>::iterator it=mylist.begin(); it!=mylist.end(); ++it)
        cout << ' ' << *it;
    cout << '
';

    return 0;
}
输出结果：
mylist contains: 36 20

• unique  //删除重复值

void unique();  //只能删除相邻的重复元素，然后保留第一个值，因此这个函数只对排好序的list有用

template <class BinaryPredicate>

void unique (BinaryPredicate binary_pred);  //binary_pred可以是函数，也可以是class，但它需要有两个参数，且类型跟list中存储的值类型相同，满足某个条件就返回true

// list::unique
#include <iostream>
#include <cmath>
#include <list>
using namespace std;
// a binary predicate implemented as a function:
bool same_integral_part (double first, double second) { return ( int(first)==int(second) ); }

// a binary predicate implemented as a class:
struct is_near {
    bool operator() (double first, double second) { return (fabs(first-second)<5.0); }
};

int main () {
    double mydoubles[] = { 12.15, 2.72, 73.0, 12.77, 3.14,
                       12.77, 73.35, 72.25, 15.3, 72.25 };
    list<double> mylist (mydoubles,mydoubles+10);
    cout << "mylist contains:";
    for (list<double>::iterator it = mylist.begin(); it != mylist.end(); ++it)
        cout << ' ' << *it;
    cout << '
';
    
    mylist.unique();
    cout << "mylist contains:";
    for (list<double>::iterator it = mylist.begin(); it != mylist.end(); ++it)
        cout << ' ' << *it;
    cout << '
';

    mylist.sort();             //  2.72,  3.14, 12.15, 12.77, 12.77,
                             // 15.3,  72.25, 72.25, 73.0,  73.35

    mylist.unique();           //  2.72,  3.14, 12.15, 12.77
                             // 15.3,  72.25, 73.0,  73.35
    cout << "mylist contains:";
    for (list<double>::iterator it = mylist.begin(); it != mylist.end(); ++it)
        cout << ' ' << *it;
    cout << '
';

    mylist.unique (same_integral_part);  //  2.72,  3.14, 12.15
                                       // 15.3,  72.25, 73.0
    cout << "mylist contains:";
    for (list<double>::iterator it = mylist.begin(); it != mylist.end(); ++it)
        cout << ' ' << *it;
    cout << '
';

    mylist.unique (is_near());           //  2.72, 12.15, 72.25

    cout << "mylist contains:";
    for (list<double>::iterator it = mylist.begin(); it != mylist.end(); ++it)
        cout << ' ' << *it;
    cout << '
';

  return 0;
}
输出结果：
mylist contains: 12.15 2.72 73 12.77 3.14 12.77 73.35 72.25 15.3 72.25
mylist contains: 12.15 2.72 73 12.77 3.14 12.77 73.35 72.25 15.3 72.25
mylist contains: 2.72 3.14 12.15 12.77 15.3 72.25 73 73.35
mylist contains: 2.72 3.14 12.15 15.3 72.25 73
mylist contains: 2.72 12.15 72.25

• merge  //合并有序的list

void merge(list &x);  //会将列表x中的元素按默认的顺序移入当前列表当中，此时列表x为空，当前列表仍为有序列表

template<class Compare>

void merge (list& x, Compare comp);  //comp可以为一个函数，要求有两个参数且参数类型跟list中存储的元素类型相同，当满足条件时返回true，merge就按照这个条件将两个列表合并

// list::merge
#include <iostream>
#include <list>
using namespace std;
// compare only integral part:
bool mycomparison (double first, double second) { return ( (first)<(second) ); }

int main () {
    list<double> first, second;

    first.push_back (3.1);
    first.push_back (2.2);
    first.push_back (2.9);

    second.push_back (3.7);
    second.push_back (7.1);
    second.push_back (1.4);

    first.sort();
    second.sort();

    first.merge(second);
    cout << "first contains:";
    for (list<double>::iterator it = first.begin(); it != first.end(); ++it)
        cout << ' ' << *it;
    cout << '
';
    // (second 现在为空)

    second.push_back (2.1);
    second.push_back(2.5);

    first.merge(second,mycomparison);
    cout << "first contains:";
    for (list<double>::iterator it = first.begin(); it != first.end(); ++it)
        cout << ' ' << *it;
    cout << '
';

  return 0;
}
输出结果：
first contains: 1.4 2.2 2.9 3.1 3.7 7.1
first contains: 1.4 2.1 2.2 2.5 2.9 3.1 3.7 7.1

• sort  //排序

void sort();  //默认升序排列

template <class Compare>

void sort (Compare comp);  //comp可以是一个函数，要求有两个参数，类型跟list中元素类型相同，满足条件时返回true，sort()函数就按照comp中制定的规则对元素进行排序

// list::sort
#include <iostream>
#include <list>
#include <string>
#include <cctype>
using namespace std;
// comparison, not case sensitive.
bool compare_nocase (const string& first, const string& second) {
    unsigned int i = 0;
    while ((i < first.length()) && (i < second.length()) ) {
        //将大写字母转为小写字母
        if (tolower(first[i]) < tolower(second[i])) return true;
        else if (tolower(first[i]) > tolower(second[i])) return false;
        ++i;
    }
    return ( first.length() < second.length() );
}

int main () {
    list<string> mylist;
    list<string>::iterator it;
    mylist.push_back ("one");
    mylist.push_back ("two");
    mylist.push_back ("Three");

    mylist.sort();

    cout << "mylist contains:";
    for (it = mylist.begin(); it != mylist.end(); ++it)
        cout << ' ' << *it;
    cout << '
';

    mylist.sort(compare_nocase);

    cout << "mylist contains:";
    for (it = mylist.begin(); it != mylist.end(); ++it)
        cout << ' ' << *it;
    cout << '
';

  return 0;
}
输出结果：
mylist contains: Three one two
mylist contains: one Three two

• reverse  //逆序：

void reverse();  //将list中元素的顺序逆转过来

// reversing list
#include <iostream>
#include <list>
using namespace std;
int main () {
    list<int> mylist;

    for (int i = 1; i < 10; ++i) mylist.push_back(i);

    mylist.reverse();

    cout << "mylist contains:";
    for (list<int>::iterator it = mylist.begin(); it != mylist.end(); ++it)
        cout << ' ' << *it;
    cout << '
';

  return 0;
}
输出结果：
mylist contains: 9 8 7 6 5 4 3 2 1

Observers:

• get_allocator  //返回一个跟该list有关的分配器对象

allocator_type get_allocator() const;  //可以用来给数组动态分配空间

// list::get_allocator
#include <iostream>
#include <list>
using namespace std;
int main () {
    list<int> mylist;
    int * p;

    // allocate an array of 5 elements using mylist's allocator:
    p = mylist.get_allocator().allocate(5);

    // assign some values to array
    for (int i = 0; i < 5; ++i) p[i] = i;

    cout << "The allocated array contains:";
    for (int i = 0; i < 5; ++i) cout << ' ' << p[i];
    cout << '
';

    mylist.get_allocator().deallocate(p,5);

    return 0;
}
输出结果：
The allocated array contains: 9 8 7 6 5 4 3 2 1