How can I remove elements from an std::set while iterating over it
My first attempt looks like:
set<T> s; for(set<T>::iterator iter = s.begin(); iter != s.end(); ++iter) { //Do some stuff if(/*some condition*/) s.erase(iter--); } But this is problematic if we want to remove the first element from the set because iter-- invalidates the iterator.
What's the standard way to do this?
Standard way is to do something like
for(set<T>::iterator iter = s.begin(); iter != s.end();) { if(/*some condition*/) { s.erase(iter++); } else { ++iter; } } By the first condition we are sure, that iter will not be invalidated anyway, since a copy of iter will be passed into erase, but our iter is already incremented, before erase is called.
In C++11, the code will be like
for(set<T>::iterator iter = s.begin(); iter != s.end();) { if(/*some condition*/) { iter = s.erase(iter); } else { ++iter; } } 
