C++ Map快速入门

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

MemberWhere definedDescriptionkey_typeAssociative Containermap中的key类型data_typePair Associative Containerkey关联的值类型value_typePair Associative Container对象类型, pair<const key_type, data_type>,存储在map中key_compareSorted Associative ContainerFunction object 通过顺序比较value_compareSorted Associative ContainerFunction object that compares two values for ordering.pointerContainerPointer to T.referenceContainerReference to Tconst_referenceContainerConst reference to Tsize_typeContainerAn unsigned integral type.difference_typeContainerA signed integral type.iteratorContainerIterator used to iterate through a map. [1]const_iteratorContainerConst iterator used to iterate through a map.reverse_iteratorReversible ContainerIterator used to iterate backwards through a map.[1]const_reverse_iteratorReversible ContainerConst iterator used to iterate backwards through amap.iterator begin()ContainerReturns an iterator pointing to the beginning of the map.iterator end()ContainerReturns an iterator pointing to the end of themap.const_iterator begin() constContainerReturns a const_iterator pointing to the beginning of themap.const_iterator end() constContainerReturns a const_iterator pointing to the end of the map.reverse_iterator rbegin()Reversible ContainerReturns a reverse_iterator pointing to the beginning of the reversed map.reverse_iterator rend()Reversible ContainerReturns a reverse_iterator pointing to the end of the reversed map.const_reverse_iterator rbegin() constReversible ContainerReturns a const_reverse_iterator pointing to the beginning of the reversed map.const_reverse_iterator rend() constReversible ContainerReturns a const_reverse_iterator pointing to the end of the reversed map.size_type size() constContainerReturns the size of the map.size_type max_size() constContainerReturns the largest possible size of the map.bool empty() constContainertrue if the map's size is 0.key_compare key_comp() constSorted Associative ContainerReturns the key_compare object used by the map.value_compare value_comp() constSorted Associative ContainerReturns the value_compare object used by themap.map()ContainerCreates an empty map.map(const key_compare& comp)Sorted Associative ContainerCreates an empty map, using comp as thekey_compare object.

template <class InputIterator>map(InputIterator f, InputIterator l)

Unique Sorted Associative ContainerCreates a map with a copy of a range.

template <class InputIterator>map(InputIterator f, InputIterator l,    const key_compare& comp)

Unique Sorted Associative ContainerCreates a map with a copy of a range, using compas thekey_compare object.map(const map&)ContainerThe copy constructor.map& operator=(const map&)ContainerThe assignment operatorvoid swap(map&)ContainerSwaps the contents of two maps.

pair<iterator, bool>insert(const value_type& x)

Unique Associative ContainerInserts x into the map.

iterator insert(iterator pos,                const value_type& x)

Unique Sorted Associative ContainerInserts 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 ContainerInserts a range into the map.void erase(iterator pos)Associative ContainerErases the element pointed to by pos.size_type erase(const key_type& k)Associative ContainerErases the element whose key is k.void erase(iterator first, iterator last)Associative ContainerErases all elements in a range.void clear()Associative ContainerErases all of the elements.iterator find(const key_type& k)Associative ContainerFinds an element whose key is k.const_iterator find(const key_type& k) constAssociative ContainerFinds an element whose key is k.size_type count(const key_type& k)Unique Associative ContainerCounts the number of elements whose key is k.iterator lower_bound(const key_type& k)Sorted Associative ContainerFinds the first element whose key is not less thank.const_iterator lower_bound(const key_type& k) constSorted Associative ContainerFinds the first element whose key is not less thank.iterator upper_bound(const key_type& k)Sorted Associative ContainerFinds the first element whose key greater than k.const_iterator upper_bound(const key_type& k) constSorted Associative ContainerFinds the first element whose key greater than k.

pair<iterator, iterator> equal_range(const key_type& k)

Sorted Associative ContainerFinds a range containing all elements whose key is k.

pair<const_iterator, const_iterator> equal_range(const key_type& k) const

Sorted Associative ContainerFinds a range containing all elements whose key is k.

data_type& operator[](const key_type& k) [3]

mapSee below.

bool operator==(const map&,                 const map&)

Forward ContainerTests two maps for equality. This is a global function, not a member function.

bool operator<(const map&,                const map&)

Forward ContainerLexicographical comparison. This is a global function, not a member function.