I want to erase some elements in my std::map.
I wrote erase + remove_if technique which I always do with other sequence containers.
But it wasn't compile with map. Why?
And How can I do this job?
std::map<int, int> m;
bool foo(const std::pair<int, int>& p)
{
return p.second > 15;
}
int _tmain(int argc, _TCHAR* argv[])
{
m.insert(make_pair(0, 0));
m.insert(make_pair(1, 10));
m.insert(make_pair(2, 20));
m.insert(make_pair(3, 30));
m.erase(
remove_if(m.begin(), m.end(), foo),
m.end()); // compile error
return 0;
}
Write it like this for map, since remove_if
won't work for map
iterators (it merely puts offending elements at the end, and map
iterators don't allow for this):
template <typename Map, typename F>
void map_erase_if(Map& m, F pred)
{
typename Map::iterator i = m.begin();
while ((i = std::find_if(i, m.end(), pred)) != m.end())
m.erase(i++);
}
or if you like one-liners:
template <typename Map, typename F>
void map_erase_if(Map& m, F pred)
{
for (typename Map::iterator i = m.begin();
(i = std::find_if(i, m.end(), pred)) != m.end();
m.erase(i++));
}