Compare two ISO 8601 in c++

Question

I want to right a function that would compare two ISO 6801 time stamps and return the most recent one. I'm having trouble figuring out an easy way to create a function

For example Given string s1 = 2012-10-10 09:42:00; and string s2 = 2012-10-10 09:52:00;

compare_timestamp(s1,s2) would return s2

ISO 8601 is designed so that you can just compare the strings lexicographically (e.g. via `strcmp`) to determine their order in time. — Nemo, Dec 19 '12 at 02:03
@Nemo so convert both of `std::string`'s to `const char*` then use `strcmp`? — pyCthon, Dec 19 '12 at 02:13

score 4 · Accepted Answer · answered Dec 19 '12 at 02:13

4

If you juste need to find the more recent, a string comparison is sufficent.

string &compare_timestamp(string &s1, string &s2) {
    return s1.compare(s2) > 0 ? s1 : s2;
}

answered Dec 19 '12 at 02:13

BAK

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1

I have to downvote this for not being as straightforward as it could be. – David Stone Dec 19 '12 at 04:15

score 2 · Answer 2 · edited May 23 '17 at 12:15

std::string & compare_timestamp(std::string & lhs, std::string & rhs) {
    return std::max(lhs, rhs);
}
std::string const & compare_timestamp(std::string const & lhs, std::string const & rhs) {
    return std::max(lhs, rhs);
}

Now, a better solution would be to create a TimeStamp class rather than working with a std::string directly. The TimeStamp could internally hold a std::string and overload operator< to just defer to std::string::operator<, but you would be using strong types

Compare two ISO 8601 in c++

2 Answers2