Normally, if I want to find whether the key exists in map STL(C++), the first thing come up to my mind is if(map1[key1])
. However, this is wrong, because if there is no key equals to key1
, map1[key1]
will return 0 and if there is a key1
but its value is 0
, then it will also return 0; So this method is not feasible.