Question

Is there any way to get all keys from an STL hash_map? Or I have to use something like set or hash_set to record them before insertion?

Answer 1

hash_map<string, void *> hashMap;

vector<string> keys;
keys.reserve(hashMap.size());

for (hash_map<string, void *>::iterator iter = hashMap.begin(); 
                                        iter != hashMap.end(); 
                                        ++iter)
{
    keys.push_back(iter->first);
}