stl set

stl set

[Aseem Rastogi]

Hi,

I am a bit confused about STL sets. STL set takes a comparator function 
as input which returns true if first argument is less than second 
argument, false otherwise. How does this detect equal elements ?

For eg. set<int> will not allow one int to be inserted twice. How does 
it check for equality when comparator function doesn't provide that info ?

I tries to go through set code in stl_set.h but couldn;t get anything.

Thanks in advance.

Regards,
Aseem.

-- 
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Re: stl set

[Andreas Pfeil]

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It does so by comparing twice:
if a is not smaller b and b is not smaller a, then obviously they have
to be equal with respect to this comparison function.

Andreas

Aseem Rastogi wrote:
> Hi,
> 
> I am a bit confused about STL sets. STL set takes a comparator function
> as input which returns true if first argument is less than second
> argument, false otherwise. How does this detect equal elements ?
> 
> For eg. set<int> will not allow one int to be inserted twice. How does
> it check for equality when comparator function doesn't provide that info ?
> 
> I tries to go through set code in stl_set.h but couldn;t get anything.
> 
> Thanks in advance.
> 
> Regards,
> Aseem.
> 

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