I see a golf game ;) this one only goes for it if it's truly undefined 
perl -e '$_=shift;print(defined$_?$_:0)'

[download]
this one is shorter but also matches an empty string 
perl -e '$_=shift;print(/^$/?0:$_)'

[download]

In reply to Re: Stringifying undefs by bageler
in thread Stringifying undefs by BUU

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