1BEGIN { 2 a[i] = "null" # i is initially undefined 3 for (i in a) { # i is null string 4 print length(i), a[i] # , typeof(i) # 0 null 5 print (i==0), (i=="") # 1 1 should be 0 1 6 } 7 print a[""] # null 8 print a[0] # 9 10 b[$2] = "null also" # $2 is also undefined 11 for (j in b) { 12 print length(j), a[j] # , typeof(i) # 0 null 13 print (j==0), (j=="") # 1 1 should be 0 1 14 } 15 print b[""] # null 16 print b[0] # 17} 18