Hello,
I would like to know what the exact requirements are for classes that use
associative containers in terms of which overloaded operators and
constructors they must provide. For instance, if I have a class
called Foo, and declare and std::map<Foo>, then what other
methods and constructors must Foo implement for
std::map<Foo> to work as expected besides
bool operator<(const Foo &foo) const;
Thanks,
Neil 1 1511
"Neil Zanella" <nz******@cs.mu n.ca> wrote... I would like to know what the exact requirements are for classes that use associative containers in terms of which overloaded operators and constructors they must provide. For instance, if I have a class called Foo, and declare and std::map<Foo>, then what other methods and constructors must Foo implement for std::map<Foo> to work as expected besides
bool operator<(const Foo &foo) const;
Actually, that is not even a requirement. You may supply your own
comparator for the keys. The requirement for the comparator 'comp',
though, is that in order for two keys 'k1' and 'k2' to be _equivalent_,
comp(k1,k2) should be false _as_well_as_ comp(k2,k1).
BTW, you cannot declare std::map<Foo> because std::map needs at least
two template arguments.
Get yourself a copy of Nicolai Josuttis' "The C++ Standard Library".
It will be the best book you've used. Trust me.
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