How would I sort a vector of strings by the size of the string? pal is a vector containing strings. I call sort using the function greater to sort the strings by size.
Code:psuedocode: sort(pal.begin(), pal.end(), greater); ................................. bool greater(string a, string b) { int i, j; i = a.size(); j = b.size(); return i > j; }
How does it not work?
By the way, you should be passing the strings by const reference in the comparator.
Look up a C++ Reference and learn How To Ask Questions The Smart WayOriginally Posted by Bjarne Stroustrup (2000-10-14)
The idea is correct.
You could rename the comparison function to something like longer to describe better what it does (there is already std::greater and it means comparing with > operator) and shorten it just to a single return statement.
I might be wrong.
Quoted more than 1000 times (I hope).Thank you, anon. You sure know how to recognize different types of trees from quite a long way away.
Just like that?
I was getting an error, reference to ‘greater’ is ambiguous, along with several other errors. When I changed greater to longer it works fine. I didn't realize there was already a std::greater. Thanks.
Ah well, at least now you know that you should post about the problem, including any error messages
Incidentally, you should consider turning the comparator into a function object:
You could easily turn it into a class template too, if you see a need to do so.Code:struct Longer { bool operator()(const std::string& lhs, const std::string& rhs) const { return lhs.size() > rhs.size(); } };
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Are you including the <functional> header and using a using namespace std; directive?
If so, it probably sees your greater() function as well as std::greater and doesn't know which one you're talking about.
Try renaming your function to longer() as previously suggested, or get rid of using namespace std;
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Or fully qualify the global function as ::greater, but frankly renaming it is the best option even if there was no name collision.
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