How can I avoid “for” loops with an “if” condition inside them with C++?

Question

With almost all code I write, I am often dealing with set reduction problems on collections that ultimately end up with naive \"if\" conditions inside of them. Here\'s a simple

Answer 1

Instead of creating a new algorithm, as the accepted answer does, you can use an existing one with a function that applies the condition:

std::for_each(first, last, [](auto&& x){ if (cond(x)) { ... } });

Or if you really want a new algorithm, at least reuse for_each there instead of duplicating the iteration logic:

template 
  void
  for_each_if(Iter first, Iter last, Pred p, Op op) {
    std::for_each(first, last, [&](auto& x) { if (p(x)) op(x); });
  }