Shell Programming and Scripting

Imagine 2 files f1 f2:

Code:

file1_l1_c1 code_to_find file1_l1_c3
file1_l2_c1 file1_code2 file1_l2_c3
file1_l3_c1 file1_code3 file1_l3_c3

Code:

file2_l1_c1 file2_l1_c2 code_to_find
file2_l2_c1 file2_l2_c2 file2_code5
file2_l3_c1 file2_l3_c2 file2_code3

Say we want to print lines from f2 having "code_to_find" as $3. I go the classical way with a

Code:

FNR == NR && /file1_l1/ {
	code[$2] = 1
	next
}

code[$3] {
	print
}

As expected the output is: file2_l1_c1 file2_l1_c2 code_to_find

Now, if I print the code[] array in the END block:END{ for (i in code) print "code[" i "]=" code[i]}

I would have expected that block to produce the only code[index] with a value i.e. code[code_to_find]=1

But to my great surprise, it returns this:

Code:

code[file1_l3_c3]=
code[code_to_find]=1
code[file2_code3]=
code[file1_l2_c3]=
code[file2_code5]=

How come that awk assigns the NULL value to the array with $3 from all files as index? Kind of weird to me.