Which one is better to check if the key is in the hash_map in C++? at with try…catch block or find with iterator comparison?

Question

As far as I know there are two basics ways to check if an item is in the hash_map:

Let's say we have a hash_map: hash_map<string, int> amap

If we are gonna check whether "abc" is in the map then we can do

hash_map<string, int>::iterator itr = amap.find("abc");
if (itr != amap.end()) //in the map

or:

try {
    int value = amap.at("abc");
}
catch(out_of_range& e) {
    //not there    
}

Just wanna know which one is better? for efficiency concern?

Answer 1

Use find() . Testing the iterator is almost certainly going to be much cheaper than catching an exception.