How do I find all the positions of a substring in a string?

Question

I want to search a large string for all the locations of a string.

Answer 1

I'll add for completeness, there is another approach that is possible with std::search, works like std::string::find, difference is that you work with iterators, something like:

std::string::iterator it(str.begin()), end(str.end());
std::string::iterator s_it(search_str.begin()), s_end(search_str.end());

it = std::search(it, end, s_it, s_end);

while(it != end)
{
  // do something with this position..

  // a tiny optimisation could be to buffer the result of the std::distance - heyho..
  it = std::search(std::advance(it, std::distance(s_it, s_end)), end, s_it, s_end);
}

I find that this sometimes outperforms std::string::find, esp. if you represent your string as a vector.