Thread: Sort a std::vector<int>

Yes, ofcourse you are right. I thought that example should have been the same as the real example that I have below now.
This might then be a bit different. The thing is that I have 6 strings that look like this below that I then put to a std::vector<string> and when I sort this vector, the output will look like this: (Notice the beginning number)

"3,01/05/2000";
"2,01/05/2001";
"1,01/05/2002";
"- 3,01/05/2003";
"- 2,01/05/2004";
"- 1,01/05/2005";

The thing is that I want to sort this in order for the first number like below. Why I want to do this is that I want the date that is after in the string to follow the number.
I dont know if this is possible ?

"3,01/05/2000";
"2,01/05/2001";
"1,01/05/2002";
"- 1,01/05/2005";
"- 2,01/05/2004";
"- 3,01/05/2003";

Code:

std::vector<string> Numbers;
string Number1 = "- 1,01/05/2000";
string Number2 = "- 2,01/05/2000";
string Number3 = "- 3,01/05/2000";
string Number4 =  "1,01/05/2000";
string Number5 =  "2,01/05/2000";
string Number6 =  "3,01/05/2000";

Numbers.push_back(Number1);
Numbers.push_back(Number2);
Numbers.push_back(Number3);
Numbers.push_back(Number4);
Numbers.push_back(Number5);
Numbers.push_back(Number6);

std::sort(Numbers.rbegin(), Numbers.rend()); //Sort the Vectorstd::vector<int>

It's possible, but strings are sorted lexicographically by default. You need a custom comparison functor.

For simplicity, I'm assuming the space above is not there. You'll have to do that adaption yourself.

Code:

struct rcompare_sortkey
{
  bool operator()(const std::string &lhs, const std::string &rhs {
    std::string::size_type lp = lhs.find(","), rp = rhs.find(",");
    return boost::lexical_cast<int>(lhs.substring(0, lp))
        > boost::lexical_cast<int>(rhs.substring(0, rp));
  }
};

std::sort(Numbers.begin(), Numbers.end(), rcompare_sortkey());

Note that the functor is a greater-than, so you can use the normal iterators.

Oh yeah, of course. You need to #include <boost/lexical_cast.hpp> from the Boost libraries.