map & find()

[vertigo]

Hello
i created map<myclass1*,myclass2*> object.
I have problem with find function. It only works when
myclass1* is string or int (it does not work for char* and myclass1*).
Is it normal or i have made mistake somewhere ?
How does find() compares objects ? Maybe i should have written some
compare() function ?

Thanx
Michal

[John Harrison]

"vertigo" <ax***@wp.pl> wrote in message
news:ci**********@nemesis.news.tpi.pl...

Hello
i created map<myclass1*,myclass2*> object.
I have problem with find function. It only works when
myclass1* is string or int (it does not work for char* and myclass1*).
Is it normal or i have made mistake somewhere ?
How does find() compares objects ?
If the objects are pointers then it compares pointers, which is almost never
what you want to do.
Maybe i should have written some
compare() function ?

Yes or a comparison functor, either can work.

struct Comp
{
bool operator()(const myclass1* x, myclass1* y) const
{
// return true if x is less than y
}
};

map<myclass1*,myclass2*,Comp> my_map;

john