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Re: [bug-gawk] Compatible way to test if a variable is set
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From: |
Andrew J. Schorr |
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Subject: |
Re: [bug-gawk] Compatible way to test if a variable is set |
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Date: |
Tue, 27 Nov 2018 18:21:16 -0500 |
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User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Sun, Nov 25, 2018 at 11:52:03AM -0600, Peng Yu wrote:
> I can use SYMTAB to test if a variable has been set or not. But this
> may not work in other variants of awk (e.g., mawk does not have
> SYMTAB)
>
> awk -e 'BEGIN { print("foo" in SYMTAB); print "NR" in SYMTAB }'
>
> Is there a way to test if a variable is set that may be used across
> gawk and other variants (such as mawk)?
What's your actual usage case? If it equals zero and "", it is most
likely undefined, e.g.:
function undef(x) {
return (x == "") && (x == 0)
}
Regards,
Andy