How to display the longest line from user input - linux

Question

I have a shell script that need to ask the user for 4 lines of input. Then I need to display the longest line that was entered, and then whole input is gotta go into the file.
That is what i got so far:
#!/bin/bash
lines=()
echo "Please enter 4 lines of text: "
for ((i=1; i<=4; i++)); do
IFS= read -p "" -r line && lines+=("$line")
done
echo "The longest line you entered was: "
max=0
for((i=0;i<4;i++)); do
len=${#lines}
if [[ len -gt max ]] ; then
max=$len
long="${lines}"
fi
done
echo longest line="${long}" length="${max}"
echo "I'm now putting the four lines you entered into a text file called \"mylines.txt\"..."
printf "%s\n" "${lines[#]}" > lines.txt
This is not happening for me, can you tell me what am I doing wrong?
Thanks

Answer 1

You can figure out longest line and length in first for loop:
#!/bin/bash
lines=()
max=0
echo "Please enter 4 lines of text: "
for ((i=1; i<=4; i++)); do
IFS= read -r line
lines+=("$line")
[[ ${#line} -gt $max ]] && { max=${#line}; long="$line"; }
done
echo longest line="${long}" length="${max}"
echo "I'm now putting the four lines you entered into a text file called \"mylines.txt\"..."
printf "%s\n" "${lines[#]}" > lines.txt

Answer 2

Using your exact Example you would just need to actually loop through the array by specifying an index $i when setting your len and long variables.
#!/bin/bash
lines=()
echo "Please enter 4 lines of text: "
for ((i=1; i<=4; i++)); do
IFS= read -p "" -r line && lines+=("$line")
done
echo "The longest line you entered was: "
max=0
for((i=0;i<4;i++)); do
#See how I added the [$i] this will allow you to get the length of each item in the array
len=${#lines[$i]}
if [[ len -gt max ]] ; then
max=$len
#This gets the item in the array to set the value of $long to it.
long="${lines[$i]}"
fi
done
echo longest line="${long}" length="${max}"
echo "I'm now putting the four lines you entered into a text file called \"mylines.txt\"..."
printf "%s\n" "${lines[#]}" > lines.txt
Outputs:
Please enter 4 lines of text:
one
two
three
four
The longest line you entered was:
longest line=three length=5
I'm now putting the four lines you entered into a text file called "mylines.txt"...