CODEWITHSUNDEEP
c++stringsorting
ak2
ak2

Reputation: 136

Compare function for sorting vector of strings (each string is a number) C++

I'm trying to use the following comparison function for sorting a vector<string> , in which each string is a number (possibly large number upto 10^100). But I'm getting a debug assertion failure error in VS2010.

bool compareNumberStrings (const string &a, const string &b) 
{
    if (a.length () < b.length ()) 
        return true;

    if (a.length () == b.length ()) 
    {
        int i;
        for (i=0; i<a.length() && a[i] == b[i]; i++);

        if (i != a.length ()) 
            return a[i] < b[i];
        else 
            return true;
    }

    return false;
}

Upvotes: 0

Views: 95

Answers (2)

Zac Howland
Zac Howland

Reputation: 15872

You could stop storing numbers in strings and use a big number library (e.g. GMP MP)

Upvotes: 0

Sebastian Redl
Sebastian Redl

Reputation: 71989

You're returning true when the strings are completely equal. This is a violation of the requirements: the function must define a strict weak ordering, i.e. f(x, x) must return false. Your function returns true, and the library might well contain a check that this doesn't happen.

Upvotes: 6

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