Removing duplicate letters from string [duplicate]

Question

Is there a way to remove duplicate characters from a string like they can be removed from vectors as below

sort( vec.begin(), vec.end() );
vec.erase( unique( vec.begin(), vec.end() ), vec.end() );

or do I just have to code up a basic solution for it? What I have thought:

I could add all the characters into a set

Answer 1

The whole point of C++’ algorithm and container design is that the algorithms are – as far as possible – container agnostic.

So the same algorithm that works on vectors works – of course! – on strings.

std::sort(str.begin(), str.end());
str.erase(std::unique(str.begin(), str.end()), str.end());

The same even works on old-style C strings – with the small difference that you cannot erase their tails, you need to manually truncate them by re-setting the null terminating character (and there are no begin and end member functions so you’d use pointers to the first and one-past-last character).