Re: hash_map not reporting true size when used with hash_comp

"Igor Tandetnik" <>
Fri, 28 Dec 2007 08:11:59 -0500
"Nilesh" <> wrote in message

I have observed that when we use the hash_comp and define our own
comparison function, hash_map::size() always reports the size of 1,
doesn't matter how many elements we add in the map. We have to use the
hash_comp with user defined comparison function to use the key as

This just means your comparison function makes all keys compare equal to
each other, so only one is ever stored.

struct eqint
bool operator()(int i1, int i2) const
return true ;
return false ;

typedef hash_map<int, int, hash_compare<int, eqint>> MYHMAP2;

The second parameter of hash_compare should be a "less than" comparator,
not an "equals to" one.
With best wishes,
    Igor Tandetnik

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