[bug-gawk] How to test if a variable is uninitialized or is just a variable that happens to be an empty string?

[Peng Yu]

Hi,

I'm not able to find a function to test if a variable is uninitialized
or is just a variable that happens to be an empty string in the
manual. Is there such a function in awk? Thanks!

~/linux/test/awk/lang/variable/undefined$ cat main.sh
#!/usr/bin/env bash

echo | awk 'BEGIN{print "^" x "$"}'
echo | awk 'BEGIN{if(x=="") { print "Hello World!" }}'
echo | awk 'BEGIN{x=""; if(x=="") { print "Hello World!" }}'

-- 
Regards,
Peng