Need a map but only need to know if contained?

Question

I'm wondering if there is a more appropriate structure for my needs.

I need to have a dictionary or strings (words). All I need to know is if a given word is in the dictionary.

It seems like a waste of memory to make a map of string,string. Is there a better way?

Thanks

should you eventually have a string-string dictionary? – sithereal Jun 05 '12 at 03:57 — sithereal, Jun 05 '12 at 03:57

score 5 · Accepted Answer · answered Jun 05 '12 at 03:49

5

Use a std::set<string>. You can use std::set::find to check whether a word exists or not.

answered Jun 05 '12 at 03:49

Naveen

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score 0 · Answer 2 · answered Jun 05 '12 at 03:50

0

What you want is a std::set< std::string >.

answered Jun 05 '12 at 03:50

K-ballo

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score 0 · Answer 3 · answered Jun 05 '12 at 03:56

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Naveen and K-ballo's answers are right. Here's something that might help you while choosing the right STL container for your needs. Note: This does not take into account C++11 types, but it will help you get started with the STL: enter image description here

answered Jun 05 '12 at 03:56

Carl

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Shameless plug: the question was asked to redraw this diagram for C++11. I proposed a text alternative: http://stackoverflow.com/questions/10699265/how-can-i-efficiently-select-a-standard-library-container-in-c11/10701102#10701102 – Matthieu M. Jun 05 '12 at 07:26

score 0 · Answer 4 · answered Jun 05 '12 at 03:58

An alternative to std::set is std::unordered_set. The first is typically implemented as a red-black tree (logarithmic complexity) and the second is a hash table (average constant-time complexity). unordered_set is available in C++11, C++03 TR1, and Boost.

Need a map but only need to know if contained?

4 Answers4