CODEWITHSUNDEEP
c++stringiteratorfind
user673679
user673679

Reputation: 1366

Find substring in string with iterators

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); // ???

Upvotes: 0

Views: 1100

Answers (2)

user4815162342
user4815162342

Reputation: 154876

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.

Upvotes: 0

jrok
jrok

Reputation: 55395

std::search

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

Upvotes: 11

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