Difference between map[] and map.at in C++?

Question

What is the difference in getting a value through aMap[key] and aMap.at(key) in C++?

Answer 1

In C++11 map::at exists (who knew?).

It throws an exception if the key doesn't exist, find returns aMap.end() if the element doesn't exist, and operator[] value-initializes a new value for the corresponding key if no value exists there.