Oh good, I'm glad you posted this. I had to take a phone-call while it was being discussed on the chatterbox, and when I came back the conversation had cleared.

Firstly your regexp will match anything which has a digit it in somewhere. This might not be what you want. Perhaps something like /^\s*(\d+)\s*$/ would be better, to require a sequence of digits with possible whitespace on either side. This leaves your number in $1 afterwards.

Secondly, think twice about having your input function call your input function. You could end up with a very large call stack here, killing performance and chewing memory.

I would suggest you use a loop like this: 

while (defined($_ = <STDIN>)) {
    print "Numbers only please" and next unless (/^\s*(\d+)\s*$/);
    return $1;
}

die "urk!  Out of input.\n";

[download]
This keeps reading from STDIN until we get a number (in which case we return it), or we run out of input. Plus there's no recusion involved, which is much better than calling ourselves repeatedly.

It's not a single line, but it probably does what you want, and is shorter than the original code.

Cheers,
Paul

In reply to Re: Can this If/Else be condensed into a 1 liner with a trailing If? by pjf
in thread Can this If/Else be condensed into a 1 liner with a trailing If? by jerrygarciuh

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