Using two files to search/replace a third file - arrays

Question

I have two files:
correct.txt
the sky is blue
I like eat apple
.
.
and wrong.txt
the sky are blue
I like eat apple
.
.
.
There are a lot of lines in both files.
Now, I want to correct a third file using my search in the "wrong.txt"
to correct it using the "correct.txt".
I have created two files:
readarray -t correct_array < correct.txt
readarray -t wrong_array < wrong.txt
The file to be corrected is to_be_corrected.txt
This works:
for c in "${correct_array[#]}"
do
echo "$c"
done
I tried this
for e in "${correct_array[#]}"
do
sed -i.bak 's/$wrong_array[#]/$correct_array[#]/' to_be_corrected.txt
done
But this did not work.
How can I use sed with arrays?

Answer 1

You are using single quotes (') for your sed command, so the shell is not evaluating the variables $wrong_array[#] and $correct_array[#]. Try double quotes and braces on the variables. Also, you are using the entire array with ${correct_array[#]}. You need to pair the elements together, perhaps with an index:
for ((e=0; e<"${#correct_array[#]}"; ++e)); do
sed -i.bak "s/${wrong_array[$e]}/${correct_array[$e]}/" to_be_corrected.txt
done
This iterates e over the indexes of the array (${#correct_array[#]} gives the size of the array) then e is used to index the corresponding elements of wrong_array and correct_array. Hopefully you don't have any quotes (single or double) in your text files.

Answer 2

You should always use {} with arrays. This doesn't work:
$array[1]
But this will:
${array[1]}
As pointed out by e0k you should also use double quoted otherwise the variable won't be expanded to it's actual value.
Don't know what exaclty your array has, but I think you want to iterate it instead of use the whole thing. Try this approach:
for i in `seq 0 $((${#correct_array[#]}-1))`; do
sed -i.bak "s/${wrong_array[$i]}/${correct_array[$i]}/" to_be_corrected.txt
done