Erase/Remove contents from the map (or any other STL container) while iterating it

Question

Allegedly you cannot just erase/remove an element in a container while iterating as iterator becomes invalid. What are the (safe) ways to remove the elements that meet a cer

Answer 1

Use the fact that the post-decrement operator returns a copy of the iterator before it decrements. Since the decremented iterator is still valid after erasing the current element, the for loop continues to operate as intended.

#include 
std::list myList;
for(int i = 0; i < 10; ++i )
{
   myList.push_back(i);
}

int cnt = 0;
for(std::list::iterator iter = myList.begin(); iter != myList.end(); ++iter)
{
   if( cnt == 5 )
   {
      myList.erase(iter--);
   }
   ++cnt;
}

Edit: Doesn't work if you attempt to erase the first element in the list....