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。
- 顺序容器:
- 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 ivec;
vector vec2(ivec);
vector c (iter.begin,iter.end);
vecotr c(5,0);
vector 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
#include
#include
using namespace std;
main()
{
vector 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::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::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
#include
using namespace std;
main()
{
// 声明二维数组的大型并且初始化
vector< vector > vI2Matrix(3, vector(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;
}
}
}
#include
#include
using namespace std;
main()
{
// Vector length of 3 initialized to 0
vector vI1Matrix(3,0);
// Vector length of 4 initialized to hold another
// vector vI1Matrix which has been initialized to 0
vector< vector > vI2Matrix(4, vI1Matrix);
// Vector of length 5 containing two dimensional vectors
vector< vector< vector > > vI3Matrix(5, vI2Matrix);
...
或者在一条语句中定义:
#include
#include
using namespace std;
main()
{
vector< vector< vector > > vI3Matrix(2, vector< vector > (3, vector(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
#include
using namespace std;
main()
{
vector< vector > vI2Matrix; // 声明二维数组
vector A, B;
vector< vector >::iterator iter_ii;
vector::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 v; 声明一个数据类型为 "T"的vector变量v. vector v(size_type n); 声明一个大小为n，包含数据类型T的vector变量 vector 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 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:
|
| = 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:
- 第一个为数据类型为int
- 第二个为类实例
// Standard Template Library example
#include
#include
using namespace std;
main()
{
list 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::iterator i;
for(i=L.begin(); i != L.end(); ++i) cout << *i << " ";
cout << endl;
return 0;
}
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
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
#include
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 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::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 |