Find substring in string with iterators

Question

I have a substring defined by two iterators (start and end). I need to check if this substring is present in another string.

Is there a standard library algorithm or string member I can use or adapt to do this without creating a whole new string object (std::string(start, end)) just for this purpose?

e.g.

struct Substring
{
    std::string::const_iterator start, end;
};

auto found = std::contains(whole.begin(), whole.end(), substring.start, substring.end); // ???

Boost has boost::algorithm::contains boost.org/doc/libs/1_55_0/doc/html/string_algo/… — CinCout
– CinCout, Commented Sep 30, 2015 at 12:50
FWIW, there's soon going to be a couple of new search methods like Boyer-Moore if you need something of that calibre. I know libstdc++ has implemented these already. — Qaz
– Qaz, Commented Sep 30, 2015 at 12:54

jrok · Accepted Answer · 2015-09-30 12:51:07Z

11

std::search

bool found = 
    std::search(hay.begin(), hay.end(), needle.begin(), needle.end()) != hay.end();

answered Sep 30, 2015 at 12:51

jrok

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1 Comment

user673679 Over a year ago

Haha. I'm not quite sure how I forgot / missed std::search. Thanks.

user4815162342 · Accepted Answer · 2015-09-30 19:59:53Z

0

You can use the std::string::find method:

auto found = (whole.find(&*substring.start, 0, substring.end - substring.start)
              != std::string::npos);

The advantage over std::search is that std::find works on strings and can be implemented using Boyer-Moore. Sadly, that is not how gcc's libstdc++ implements it.

edited Sep 30, 2015 at 19:59

answered Sep 30, 2015 at 12:53

user4815162342

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