github.com/benhoyt/goawk@v1.8.1/testdata/t.null0 (about)

     1  BEGIN { FS = ":" }
     2  {	if (a) print "a", a
     3  	if (b == 0) print "b", b
     4  	if ( c == "0") print "c", c
     5  	if (d == "") print "d", d
     6  	if (e == 1-1) print "e", e
     7  }
     8  $1 == 0	{print "$1 = 0"}
     9  $1 == "0"	{print "$1 = quoted 0"}
    10  $1 == ""	{print "$1 = null string"}
    11  $5 == 0	{print "$5 = 0"}
    12  $5 == "0"	{print "$5 = quoted 0"}
    13  $5 == ""	{print "$5 = null string"}
    14  $1 == $3 {print "$1 = $3"}
    15  $5 == $6 {print "$5 = $6"}