C++ STL：vector和list

STL 描述:

C++标准模块库是一个提供了公共编程数据结构和函数的模板类集合，如双连接表(list),配对数组(map),可扩展数组(vector),大串的存储操作(rope)等。STL库可以从http://www.sgi.com/tech/stl/ 获取。

STL可以分为以下几类：

• 容器类:
  • 顺序容器:
    • vector:动态数组变量，结构体或对象。可以插入在末尾插入数据，支持快速随机访问。
    • deque: 支持在数组的前面和后面插入元素，双端队列。
    • list: 基于链表的变量、结构或对象。可以在任何地方插入和删除元素。支持快速插入、删除。
  • 关联容器:
    • set (不允许有重复元素在set中), multiset (可以有重复元素): 平衡二叉树结构有序的数据的集合，能快速搜索。
    • map (唯一keys), multimap (允许重复keys): 关联键 - 值对的平衡二叉树结构。
  • 容器适配器:
    • stack LIFO 栈
    • queue FIFO 队列
    • priority_queue 返回最高优先级的元素，优先级队列
  • 字符串:
    • string:字符串及其操作
    • rope: 字符串存储和操作
  • bitset: 直观的存储位和操作位。
• 泛型算法：
  • 迭代器iterator: 代表容器中的位置，一个迭代器定义为一个容器类类型。
  • 算法algorithm: 提供查找，计数，搜索容器中的元素的类。
  • 智能指针auto_ptr: 关联内存指针避免内存泄露的类。

STL vector:

   初始化：

      vector<int> ivec;

      vector<int > vec2(ivec);

     vector c (iter.begin,iter.end);

      vecotr<int > c(5,0);

       vector<int> c(5);

         example 1: 用vector存储STL strings，并且用三种方法类访问vector中的元素：

#include <iostream>
#include <vector>
#include <string>

using namespace std;

main()
{
   vector<string> SS;

   SS.push_back("The number is 10");
   SS.push_back("The number is 20");
   SS.push_back("The number is 30");

   cout << "Loop by index:" << endl;

   int ii;
   for(ii=0; ii < SS.size(); ii++) //第一种方法访问
   {
      cout << SS[ii] << endl;
   }

   cout << endl << "Constant Iterator:" << endl;

   vector<string>::const_iterator cii;
   for(cii=SS.begin(); cii!=SS.end(); cii++)//第二种方法
   {
      cout << *cii << endl;
   }

   cout << endl << "Reverse Iterator:" << endl;

   vector<string>::reverse_iterator rii;
   for(rii=SS.rbegin(); rii!=SS.rend(); ++rii)// 第三种方法
   {
      cout << *rii << endl;
   }

   cout << endl << "Sample Output:" << endl;

   cout << SS.size() << endl;
   cout << SS[2] << endl;

   swap(SS[0], SS[2]);
   cout << SS[2] << endl;
}
                

用vector来表示二维、三维数组:

一个二维数组是两个vector,vector构造函数可以初始化的数组的长度，并设置初始值。

example 2：vector二维数组

#include <iostream>
#include <vector>

using namespace std;

main()
{
   // 声明二维数组的大型并且初始化
   vector< vector<int> > vI2Matrix(3, vector<int>(2,0));    

   vI2Matrix[0][0] = 0;
   vI2Matrix[0][1] = 1;
   vI2Matrix[1][0] = 10;
   vI2Matrix[1][1] = 11;
   vI2Matrix[2][0] = 20;
   vI2Matrix[2][1] = 21;

   cout << "Loop by index:" << endl;

   int ii, jj;
   for(ii=0; ii < 3; ii++)
   {
      for(jj=0; jj < 2; jj++)
      {
         cout << vI2Matrix[ii][jj] << endl;
      }
   }
}
                

example 3 ：vector三维数组

     

#include <iostream>
#include <vector>

using namespace std;

main()
{
                               // Vector length of 3 initialized to 0
   vector<int> vI1Matrix(3,0);

                               // Vector length of 4 initialized to hold another 

                               // vector vI1Matrix which has been initialized to 0
   vector< vector<int> > vI2Matrix(4, vI1Matrix);

                               // Vector of length 5 containing two dimensional vectors
   vector< vector< vector<int> > > vI3Matrix(5, vI2Matrix);

   ...

或者在一条语句中定义:

#include <iostream>
#include <vector>

using namespace std;

main()
{
   vector< vector< vector<int> > > vI3Matrix(2, vector< vector<int> > (3, vector<int>(4,0)) );

   for(int kk=0; kk<4; kk++)
   {
      for(int jj=0; jj<3; jj++)
      {
         for(int ii=0; ii<2; ii++)
         {
            cout << vI3Matrix[ii][jj][kk] << endl;
         }
      }
   }
}

使用迭代器：

    example 4:  对二维vector使用迭代器

   

#include <iostream>
#include <vector>

using namespace std;

main()
{
   vector< vector<int> > vI2Matrix;    // 声明二维数组
   vector<int> A, B;
   vector< vector<int> >::iterator iter_ii;
   vector<int>::iterator   iter_jj;

   A.push_back(10);
   A.push_back(20);
   A.push_back(30);
   B.push_back(100);
   B.push_back(200);
   B.push_back(300);

   vI2Matrix.push_back(A);
   vI2Matrix.push_back(B);

   cout << endl << "Using Iterator:" << endl;

   for(iter_ii=vI2Matrix.begin(); iter_ii!=vI2Matrix.end(); iter_ii++)
   {
      for(iter_jj=(*iter_ii).begin(); iter_jj!=(*iter_ii).end(); iter_jj++)
      {
         cout << *iter_jj << endl;
      }
   }
}
                

构造函数/声明:

 

方法/操作	描述
vector<T> v;	声明一个数据类型为 "T"的vector变量v.
vector<T> v(size_type n);	声明一个大小为n，包含数据类型T的vector变量
vector<T> v(size_type n,const T& t);	声明一个大小为n,包含数据类型为T，元素的值为t的vector变量 Declaration: vector(size_type n, const T& t)
vector<T> v(begin_iterator,end_iterator);	从迭代器开始位置到结束位置拷贝一个vector Declaration: template vector(InputIterator, InputIterator)

Size 方法/操作: 

Method/operator	Description
empty()	Returns bool (true/false). True if empty. Declaration: bool empty() const
size()	Number of elements of vector. Declaration: size_type size() const
resize(n, t=T())	Adjust by adding or deleting elements of vector so that its size is "n". Declaration: void resize(n, t = T())
capacity()	Max number of elements of vector before reallocation. Declaration: size_type capacity() const
reserve(size_t n)	Max number of elements of vector set to "n" before reallocation. Declaration: void reserve(size_t)
max_size()	Max number of elements of vector possible. Declaration: size_type max_size() const

  

其他方法和操作：

Method/operator	Description
erase() clear()	Erase all elements of vector. Declaration: void clear()
erase(iterator) erase(begin_iterator,end_iterator)	Erase element of vector. Returns iterator to next element. Erase element range of vector. Returns iterator to next element. Declarations: iterator erase(iterator pos) iterator erase(iterator first, iterator last)
= Example: X=Y()	Assign/copy entire contents of one vector into another. Declaration: vector& operator=(const vector&)
<	Comparison of one vector to another. Declaration: bool operator<(const vector&, const vector&)
==	Returns bool. True if every element is equal. Declaration: bool operator==(const vector&, const vector&)
at(index) v[index]	Element of vector. Left and Right value assignment: v.at(i)=e; and e=v.at(i); Declaration: reference operator[](size_type n)
front() v[0]	First element of vector. (Left and Right value assignment.) Declaration: reference front()
back()	Last element of vector. (Left and Right value assignment.) Declaration: reference back()
push_back(const T& value)	Add element to end of vector. Declaration: void push_back(const T&)
pop_back()	Remove element from end of vector. Declaration: void pop_back()
assign(size_type n,const T& t)	Assign first n elements a value "t".
assign(begin_iterator,end_iterator)	Replace data in range defined by iterators. Declaration:
insert(iterator, const T& t)	Insert at element "iterator", element of value "t". Declaration: iterator insert(iterator pos, const T& x)
insert(iterator pos, size_type n, const T& x)	Starting before element "pos", insert first n elements of value "x". Declaration: void insert(iterator pos, size_type n, const T& x)
insert(iterator pos, begin_iterator,end_iterator)	Starting before element "pos", insert range begin_iterator to end_iterator. Declaration: void insert(iterator pos, InputIterator f, InputIterator l)
swap(vector& v2)	Swap contents of two vectors. Declaration: void swap(vector&)

迭代器方法/操作

Method/operator	Description
begin()	Return iterator to first element of vector. Declaration: const_iterator begin() const
end()	Return iterator to end of vector (not last element of vector but past last element) Declaration: const_iterator end() const
rbegin()	Return iterator to first element of vector (reverse order). Declaration: const_reverse_iterator rbegin() const
rend()	Return iterator to end of vector (not last element but past last element) (reverse order). Declaration: const_reverse_iterator rend() const
++	Increment iterator.
--	Decrement iterator.

STL list:

两个例子:

1. 第一个为数据类型为int
2. 第二个为类实例

example 1:

// Standard Template Library example

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



main()
{
   list<int> L;
   L.push_back(0);              // Insert a new element at the end
   L.push_front(0);             // Insert a new element at the beginning
   L.insert(++L.begin(),2);     // Insert "2" before position of first argument
                                // (Place before second argument)
   L.push_back(5);
   L.push_back(6);

   list<int>::iterator i;

   for(i=L.begin(); i != L.end(); ++i) cout << *i << " ";
   cout << endl;
   return 0;
}

example 2:

     如果使用自定义类型，需要包括以下几个方面：

     a. 复制构造函数
     b.赋值运算符（=）重载

     c.小于运算符重载<

     d.等于运算符==重载

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

// STL list需要重载 operators =, == and <.

class AAA
{
   friend ostream &operator<<(ostream &, const AAA &);

   public:
      int x;
      int y;
      float z;

      AAA();
      AAA(const AAA &);
      ~AAA(){};
      AAA &operator=(const AAA &rhs);
      int operator==(const AAA &rhs) const;
      int operator<(const AAA &rhs) const;
};

AAA::AAA()   // 构造函数
{
   x = 0;
   y = 0;
   z = 0;
}

AAA::AAA(const AAA &in)   // 复制构造函数，传值
{                             
   x = copyin.x;
   y = copyin.y;
   z = copyin.z;
}

ostream &operator<<(ostream &output, const AAA &aaa)
{
   output << aaa.x << ' ' << aaa.y << ' ' << aaa.z << endl;
   return output;
}

AAA& AAA::operator=(const AAA &rhs)
{
   this->x = rhs.x;
   this->y = rhs.y;
   this->z = rhs.z;
   return *this;
}

int AAA::operator==(const AAA &rhs) const
{
   if( this->x != rhs.x) return 0;
   if( this->y != rhs.y) return 0;
   if( this->z != rhs.z) return 0;
   return 1;
}

//该函数是为了让STL list支持sort
int AAA::operator<(const AAA &rhs) const
{
   if( this->x == rhs.x && this->y == rhs.y && this->z < rhs.z) return 1;
   if( this->x == rhs.x && this->y < rhs.y) return 1;
   if( this->x < rhs.x ) return 1;
   return 0;
}

main()
{
   list<AAA> L;
   AAA Ablob ;

   Ablob.x=7;
   Ablob.y=2;
   Ablob.z=4.2355;
   L.push_back(Ablob);  // 在末尾插入一个新元素

   Ablob.x=5;
   L.push_back(Ablob);  // 传值，用默认的拷贝构造函数
                        // 
   Ablob.z=3.2355;
   L.push_back(Ablob); 

   Ablob.x=3;
   Ablob.y=7;
   Ablob.z=7.2355;
   L.push_back(Ablob); 

   list<AAA>::iterator i;

   for(i=L.begin(); i != L.end(); ++i) cout << (*i).x << " "; // print member
   cout << endl;      

   for(i=L.begin(); i != L.end(); ++i) cout << *i << " "; // print with overloaded operator
   cout << endl;

   cout << "Sorted: " << endl;
   L.sort();
   for(i=L.begin(); i != L.end(); ++i) cout << *i << " "; // print with overloaded operator
   cout << endl;

   return 0;
}

                

输出结果：

7 5 5 3 
7 2 4.2355
 5 2 4.2355
 5 2 3.2355
 3 7 7.2355
 
Sorted:
3 7 7.2355
 5 2 3.2355
 5 2 4.2355
 7 2 4.2355

STL vector 和 list 函数比较:

Function	vector	list
constructor	yes	yes
destructor	yes	yes
empty()	yes	yes
size()	yes	yes
resize()	yes	yes
capacity()	yes	no
reserve()	yes	no
max_size()	yes	yes
erase()	yes	yes
clear()	yes	yes
operator=	yes	yes
operator<	yes	yes
operator==	yes	yes
operator[]	yes	no
at()	yes	no
front()	yes	yes
back()	yes	yes
push_back()	yes	yes
pop_back()	yes	yes
assign()	yes	yes
insert()	yes	yes
swap()	yes	yes
push_front()	no	yes
pop_front()	no	yes
merge()	no	yes
remove()	no	yes
remove_if()	no	yes
reverse()	no	yes
sort()	no	yes
splice()	no	yes
unique()	no	yes