C++ Map快速入门

2015/06/19 43222

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Map是一个关联性容器

map的存储类型是pair<const key,value>的类型
任何两个元素没有相同的key值
map是
1 、构造函数
map<const char*,int>
map<const char*,int,status>
其中status为Comparison类，定义key的排序顺序，也就定义了整个map的key->value对存储顺序
bool status(const char *s1, const char* s2)
{
return strcmp(s1,s2)<0;
}
2、 迭代器
map<const char *key,const char *value>::iterator it;
it -> first; //访问key
it -> second;//访问value


3、常用函数

find(class key)//查找指定的key，返回相应的迭代器位置，找不到则迭代器处于末尾

insert(pair<class key,class value>)//插入一个pair类型的数据

clear()//清空整个map的数据

empty()//判断map是否为空，返回bool类型值

begin()/rbgeion() // 返回迭代器指向第一个/最后一个元素位置

end()/rend( ) //返回最后一个元素下一个位置/第一个元素的下一个位置


4 示例代码 

    #include "stdafx.h"  
    #include <iostream>  
    #include <map>  
    using namespace std;  
    int _tmain(int argc, _TCHAR* argv[])  
    {  
    map<int,const char *> mymap;  
    mymap[0] = "Jack";  
    mymap[1] = "Lucy";  
    mymap.insert(pair<int,const char *>(3,"Mike"));  
    mymap.insert(pair<int,const char *>(4,"Lily"));  
    cout<<"Use iterator"<<endl;  
    map<int,const char*>::iterator it = mymap.begin();  
    while (it != mymap.end())  
    {  
    cout<<it->first<<"->"<<it->second<<endl;  
    it++;  
    }  
    cout<<"Use reverse_iterator"<<endl;  
    map<int,const char*>::reverse_iterator reit = mymap.rbegin();  
    while (reit != mymap.rend())  
    {  
    cout<<reit->first<<"->"<<reit->second<<endl;  
    reit++;  
    }  
    it = mymap.find(1);  
    if ( it != mymap.end())  
    {  
    cout<<"use find(1):"<<it->second<<endl;  
    >}  
    else  
    {  
    cout<<"Cannot find(1)"<<endl;  
    }  
      
      
    mymap.clear();  
    mymap[5] = "New";  
    mymap[6] = "Temp";  
    cout<<"Current size"<<mymap.size()<<endl;  
      
      
    }

5 所有关于map的函数如下


Member Where defined Description
key_type Associative Container map中的key类型
data_type Pair Associative Container key关联的值类型
value_type Pair Associative Container 对象类型, pair<const key_type, data_type>,存储在map中
key_compare Sorted Associative Container Function object 通过顺序比较
value_compare Sorted Associative Container Function object that compares two values for ordering.
pointer Container Pointer to T.
reference Container Reference to T
const_reference Container Const reference to T
size_type Container An unsigned integral type.
difference_type Container A signed integral type.
iterator Container Iterator used to iterate through a map. [1]
const_iterator Container Const iterator used to iterate through a map.
reverse_iterator Reversible Container Iterator used to iterate backwards through a map.[1]
const_reverse_iterator Reversible Container Const iterator used to iterate backwards through amap.
iterator begin() Container Returns an iterator pointing to the beginning of the map.
iterator end() Container Returns an iterator pointing to the end of themap.
const_iterator begin() const Container Returns a const_iterator pointing to the beginning of themap.
const_iterator end() const Container Returns a const_iterator pointing to the end of the map.
reverse_iterator rbegin() Reversible Container Returns a reverse_iterator pointing to the beginning of the reversed map.
reverse_iterator rend() Reversible Container Returns a reverse_iterator pointing to the end of the reversed map.
const_reverse_iterator rbegin() const Reversible Container Returns a const_reverse_iterator pointing to the beginning of the reversed map.
const_reverse_iterator rend() const Reversible Container Returns a const_reverse_iterator pointing to the end of the reversed map.
size_type size() const Container Returns the size of the map.
size_type max_size() const Container Returns the largest possible size of the map.
bool empty() const Container true if the map's size is .
key_compare key_comp() const Sorted Associative Container Returns the key_compare object used by the map.
value_compare value_comp() const Sorted Associative Container Returns the value_compare object used by themap.
map() Container Creates an empty map.
map(const key_compare& comp) Sorted Associative Container Creates an empty map, using comp as thekey_compare object. 
template <class InputIterator>
map(InputIterator f, InputIterator l)
Unique Sorted Associative Container Creates a map with a copy of a range. 
template <class InputIterator>
map(InputIterator f, InputIterator l,
    const key_compare& comp)
Unique Sorted Associative Container Creates a map with a copy of a range, using compas thekey_compare object.
map(const map&) Container The copy constructor.
map& operator=(const map&) Container The assignment operator
void swap(map&) Container Swaps the contents of two maps. 
pair<iterator, bool>
insert(const value_type& x)
Unique Associative Container Inserts x into the map. 
iterator insert(iterator pos,
                const value_type& x)
Unique Sorted Associative Container Inserts x into the map, using pos as a hint to where it will be inserted. 
template <class InputIterator>
void insert(InputIterator, InputIterator) [2]
Unique Sorted Associative Container Inserts a range into the map.
void erase(iterator pos) Associative Container Erases the element pointed to by pos.
size_type erase(const key_type& k) Associative Container Erases the element whose key is k.
void erase(iterator first, iterator last) Associative Container Erases all elements in a range.
void clear() Associative Container Erases all of the elements.
iterator find(const key_type& k) Associative Container Finds an element whose key is k.
const_iterator find(const key_type& k) const Associative Container Finds an element whose key is k.
size_type count(const key_type& k) Unique Associative Container Counts the number of elements whose key is k.
iterator lower_bound(const key_type& k) Sorted Associative Container Finds the first element whose key is not less thank.
const_iterator lower_bound(const key_type& k) const Sorted Associative Container Finds the first element whose key is not less thank.
iterator upper_bound(const key_type& k) Sorted Associative Container Finds the first element whose key greater than k.
const_iterator upper_bound(const key_type& k) const Sorted Associative Container Finds the first element whose key greater than k. 
pair<iterator, iterator> 
equal_range(const key_type& k)
Sorted Associative Container Finds a range containing all elements whose key is k. 
pair<const_iterator, const_iterator> 
equal_range(const key_type& k) const
Sorted Associative Container Finds a range containing all elements whose key is k. 
data_type& 
operator[](const key_type& k) [3]
map See below. 
bool operator==(const map&, 
                const map&)
Forward Container Tests two maps for equality. This is a global function, not a member function. 
bool operator<(const map&, 
               const map&)
Forward Container Lexicographical comparison. This is a global function, not a member function.