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 can use for-else almost like in Python by defining two macros:

#define BREAK {CONTINUETOELSE = false; break;}
#define FORWITHELSE(x, y) {bool CONTINUETOELSE = true; x if(!CONTINUETOELSE){} y}

Now you put the for and the else inside the FORWITHELSE macro separated by a comma and use BREAK instead of break. Here is an example:

FORWITHELSE(
    for(int i = 0; i < foo; i++){
        if(bar(i)){
            BREAK;
        }
    },
    else{
        baz();
    }
)

There are two things you need to remember: to put a comma before the else and to use BREAK instead of break.

Answer 2

Yes you can achieve the same effect by:

auto it = std::begin(foo);
for (; it != std::end(foo); ++it)
     if(bar(*it))
         break;
if(it == std::end(foo))
    baz();