Question

Why isn’t there a ‘find’ function in associative std containers (map, set, etc) that returns a boolean?

Say:

std::map <int,int> mMap;
...
if ( mMap.contains(75) ) ...

I know about the find() and that I can do it this way

if ( mMap.find(75) != mMap.end() ) ...

But I feel it clutters the code more than anything else.

Why isn’t there a simpler function for this, I mean containers are quite much about finding things in them?

Answer 1

You can make your own (note, it’s “HasKey” because “Contains” would deal with values)

template <class AssocContainer>
bool HasKey(const AssocContainer& haystack,
    const typename AssocContainer::key_type& needle)
{
    return haystack.find(needle) != haystack.end();
}

map<int, int> m;
m[0] = 1;
bool b = HasKey(m, 0);