Opposite of Python for ... else

Question

The following python code will result in n (14) being printed, as the for loop is completed.

for n in range(15):
    if n == 100:
        break
else:
    print(n)

However, what I want is the opposite of this. Is there any way to do a for ... else (or while ... else) loop, but only execute the else code if the loop did break?

Answer 1

There is no explicit for...elseifbreak-like construct in Python (or in any language that I know of) because you can simply do this:

for n in range(15): 
    if n == 100:
        print(n)  
        break

If you have multiple breaks, put print(n) in a function so you Don't Repeat Yourself.

Answer 2

A bit more generic solution using exceptions in case you break in multiple points in the loop and don't want to duplicate code:

try:
    for n in range(15):
        if n == 10:
            n = 1200;
            raise StopIteration();
        if n > 4:
            n = 1400;
            raise StopIteration();      
except StopIteration:
    print n;

Answer 3

I didn't really like the answers posted so far, as they all require the body of the loop to be changed, which might be annoying/risky if the body is really complicated, so here is a way to do it using a flag. replace _break with found or something else meaningful for your use case

_break = True
for n in range(15):
    if n == 100:
        break
else:
    _break = False

if _break:
    print(n)

Another possibility if it is a function that does nothing if the loop doesn't find a match, is to return in the else: block

for n in range(15):
    if n == 100:
        break
else:
    return
print(n)