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Subject:
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Question on Hashmap
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Posted By:
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alothman
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Post Date:
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5/25/2006 10:21:35 PM
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Hello!
First, I would like to express my appreciation
for the contents of chapter 23 (it's great!)
I would like to know what's the proper
way to instantiate a hashmap, where the
Compare parameter should maintain its
default value, but the Hash function is
other than DefaultHash<Key>
template<typename Key, typename T, typename Compare = std::equal_to<Key>, typename Hash = DefaultHash<Key> >
class hashmap { //... };
I only need the Hash parameter changed.
Must I do something like:
hashmap<int, string, std::equal_to<int>, MidSquare<int> > hash1?
Second question: Since "count" is only used to check whether an
element exists, would there be any consequence in using bool as
a return type instead of size_type for the count method?
Thank you,
A. Alothman
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Reply By:
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klep
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Reply Date:
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9/3/2006 2:13:05 AM
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Unfortunately, you'd have to specify the first three arguments to use a non-default value for the fourth. The STL classes have this same drawback -- you'll sometimes find yourself looking up and providing the default for one argument just so that you can change the following one.
Scott
----
Scott J. Kleper
Author, "Professional C++"
(Wrox, 2005)
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