[bug-gawk] Compatible way to test if a variable is set

[Peng Yu]

Hi,

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)?

-- 
Regards,
Peng