While and For loop for reading from file.

Filename.txt
My First Line
My Second Line

::::While Loop:::
Program(whileloop.sh):

while read line
do
echo "$line"
done < Filename.txt

output:
My First Line
My Second Line

:::For Loop:::
Program(forloop.sh):
for line in $(cat Filename.txt)
do
echo $line
done

output:
My
First
Line
My
Second
Line

You might wonder why does the output generated by for loop is different.

Well in above example for has treated space as field separator .
But to achieve the above output you need to add next line as a separator.

Therefore the same code can be written as.
Program:
IFS=for i in $(cat Filename.txt)
do
echo $i;
done

output:
My First Line
My Second Line\n' # Specify next line as Field Separator.


for i in $(cat Filename.txt)
do
echo $i;
done

output:
My First Line
My Second Line