Limits to Map Key
Jun 19, 2013 at 6:29am
What are the requirements for the type of the key of a std::map?
On this page (http://www.cplusplus.com/reference/map/map/), I noticed that the key type has to enforce a strict ordering (which I interpret to mean implementing operator<). Is this the only requirement for the type of the key?
On this page (http://www.cplusplus.com/reference/map/map/), I noticed that the key type has to enforce a strict ordering (which I interpret to mean implementing operator<). Is this the only requirement for the type of the key?
Jun 19, 2013 at 7:06am
> Is this the only requirement for the type of the key?
Yes. Other than the obvious requirements of being CopyAssignable and Destructible.
Yes. Other than the obvious requirements of being CopyAssignable and Destructible.
Jun 19, 2013 at 11:07am
Strict weak ordering means that operator< should behave in a certain way. If
a < b and b < c then you should also have that a < c. a < a should always return false. By testing if a < b and b < a both returns false is how they can know that a and b are equal.
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