How to get the tail of a std::string?

Question

How to retrieve the tail of a std::string?

If wishes could come true, it would work like that:

string tailString = sourceString.right(6);

But this seems to be too easy, and doesn't work...

Any nice solution available?

Optional question: How to do it with the Boost string algorithm library?

ADDED:

The method should be save even if the original string is smaller than 6 chars.

Answer 1

There is one caveat to be aware of: if substr is called with a position past the end of the array (superior to the size), then an out_of_range exception is thrown.

Therefore:

std::string tail(std::string const& source, size_t const length) {   if (length >= source.size()) { return source; }   return source.substr(source.size() - length); } // tail 

You can use it as:

std::string t = tail(source, 6); 

Answer 2

Using the substr() method and the size() of the string, simply get the last part of it:

string tail = source.substr(source.size() - 6); 

For handling case of a string smaller than the tail size see Benoit's answer (and upvote it, I don't see why I get 7 upvotes while Benoit provides a more complete answer!)

Answer 3

You could do:

std::string tailString = sourceString.substr((sourceString.length() >= 6 ? sourceString.length()-6 : 0), std::string::npos);

Note that npos is the default argument, and might be omitted. If your string has a size that 6 exceeds, then this routine will extract the whole string.