Is there an equivalent to the “for … else” Python loop in C++?

Question

Python has an interesting for statement which lets you specify an else clause.

In a construct like this one:

for i in foo:
  if         


        

Answer 1

You could use a lambda function for this:

[&](){
  for (auto i : foo) {
    if (bar(i)) {
      // early return, to skip the "else:" section.
      return;
    }
  }
  // foo is exhausted, with no item satisfying bar(). i.e., "else:"
  baz();
}();

This should behave exactly like Python's "for..else", and it has some advantages over the other solutions:

• It's a true drop-in replacement for "for..else": the "for" section can have side effects (unlike none_of, whose predicate must not modify its argument), and it has access to the outer scope.
• It's more readable than defining a special macro.
• It doesn't require any special flag variables.

But... I'd use the clunky flag variable, myself.