Re: Problem using std::prev on ustring iterator

[Jonathan Wakely <gtkmm kayari org>]

On 18 March 2016 at 17:57, jeremy.harmon wrote:
> Hello,
>
> When I try to use std::prev on a ustring const_iterator nothing
> happens, operator-- works fine.
>
> Glib::ustring str = "test";
> Glib::ustring::iterator iter = str.begin();
>
> std::advance(iter);
> printf("%c\n", *iter);
>
> std::prev(iter);
> printf("%c\n", *iter);
>
> iter--;
> printf("%c\n", *iter);
>
> Output is
> e
> e
> t
>
> Any ideas why it doesn't work?

Because unlike std::advance, std::prev doesn't modify its argument, it
returns the new iterator instead.

http://en.cppreference.com/w/cpp/iterator/prev