python-like string indexing in C++

Question

Is there any (possibly, using a macros) way to get a substring of a string using python-like expression f(i:j)? Or, more specifically, resolve i:j expression into pair of indices i and j? Any ideas?

EDIT: Yes, I need :. Or ;. Basically, something that simple function or macros can't do. Just want to see if it is possible or not.

EDIT: Basically, I want to see if it is widely applicable. For arrays as well, maybe. So the question is more of a "Can I turn i:j to i j", I guess. Doesn't matter is these are std:strings or c-strings.

Are you very specific about the colon (:) in between i and j? Can you use comma (,)? — A. K.
– A. K., Commented Jul 24, 2013 at 2:25
If you are in C++, write C++ code. Don't look for ways to make your C++ look like python. — John3136
– John3136, Commented Jul 24, 2013 at 2:30
The Python-like expression would be f[i:j]. Regardless of whether it's possible and/or good, is there are a reason why you want round brackets? — jogojapan
– jogojapan, Commented Jul 24, 2013 at 2:31
Whatever you do, don't abuse macros to do this in C++, that's a bad path down which to go. — Crowman
– Crowman, Commented Jul 24, 2013 at 2:33

Robᵩ · Accepted Answer · 2013-07-24 02:58:18Z

22

I hate myself for answering, but ...

#include <iostream>
#include <string>

#define f(x) substr(true?x, false?x)

int main () {
  std::string s = "Hello, world";
  std::string y = s.f(1:4);
  std::cout << y << "\n";
}

Warning: I am a hiring manager. If I ever discover that you use this technique, I will never hire you.

edited Jul 24, 2013 at 2:58

answered Jul 24, 2013 at 2:51

Robᵩ

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4 Comments

Qaz Over a year ago

That's too brilliant to not upvote, even if it should never be used.

aaronman Over a year ago

Maybe you should include a disclaimer at the end

maksay Over a year ago

That is great, thank you:) #define g(x) f(0 x) also allows g(:3) and other cool stuff:)

John Thompson Over a year ago

This answer is wrong. The output is "ello". In Python, the output for the expression s[1:4] would be "ell".

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