怎么样删除map中指定值为value所有元素？
怎么样删除map中指定值为value所有元素？
//第一个解决方案
//erase.h
#include <algorithm>
using std::find_if;
template<class _map>
class Proxy{
typename _map::mapped_type const _value;
public:
Proxy(typename _map::mapped_type const &value):_value(value){}
bool operator()(typename _map::value_type & value){
return value.second==_value;
}
};
template<class _map>
size_t Erase(_map& m,typename _map::mapped_type const &value)
{
size_t count=0;
typename _map::iterator iter;
typename _map::iterator begin=m.begin();
typename _map::iterator end=m.end();
Proxy<_map> proxy(value);
while((iter=find_if(begin,end,proxy))!=end)
{
++count;
m.erase(iter);
begin=m.begin();
end=m.end();
}
return count;
}
//示例代码
#include <string>
#include <map>
#include "erase.h"
using std::map;
using std::string;
typedef map<int ,string> Int2Str;
int main(){
Int2Str sample;
sample[1]=string("abc");
sample[2]=string("abc");
sample[3]=string("1234");
sample[4]=string("abc");
Erase(sample,string("abc"));
return 0;
}
//******************************************************************//
//第二种方法
#include <map>
#include <string>
#include <algorithm>
#include<iostream>
using std::map;
using std::string;
using std::find_if;
using std::endl;
using std::cout;
template <class _MAP>
class DeleteAllValueProxy{
typedef typename _MAP::mapped_type const map_type;
typedef typename _MAP::iterator map_iter;
typedef typename _MAP::const_reference map_value;
map_type _val;
public:
DeleteAllValueProxy(_MAP &rmap,map_type &val)
:_val(val)
{
map_iter begin=rmap.begin();
map_iter end=rmap.end();
map_iter iter=find_if(begin,end,*this);
while (iter!=end)
{
cout<<iter->first<<" "<<iter->second<<endl;
begin=rmap.erase(iter);
end=rmap.end();
iter=find_if(begin,end,*this);
}
}
bool operator()(map_value item){
return item.second==_val;
}
};
template <class _MAP>
inline void DeleteAllValue(_MAP&rmap,typename _MAP::mapped_type const&val)
{
(DeleteAllValueProxy<_MAP>(rmap,val));
}
int main()
{
map<int,string> Int2Str;
Int2Str[5]="abc";
Int2Str[12]="abc";
Int2Str[43]="abc";
Int2Str[27]="abc";
Int2Str[1]="def";
Int2Str[8]="ghi";
Int2Str[24]="jkl";
Int2Str[56]="mn";
Int2Str[0]="opq";
DeleteAllValue(Int2Str,string("abc"));
return 0;
}
//*******************************************************************/
//第三种方法
#include <iostream>