G'day vinoth.ree,

After reading this in your OP:

"... read the first 50 characters ..."

these two lines in your code grabbed my attention:

...
my $oshort_line = substr( $oline, 0, 49 );
...
my $nshort_line = substr( $nline, 0, 49 );
...
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I don't know if you thought that's an inclusive range, or something else. See the substr documentation:

"substr EXPR,OFFSET,LENGTH"

To get the first 50 characters from a string, you need OFFSET==0 and LENGTH==50. Here's an example of what you have and one of what you probably want:

$ perl -E 'my $x = "X" x 49 . "Y" x 49; say substr $x, 0, 49'
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
$ perl -E 'my $x = "X" x 49 . "Y" x 49; say substr $x, 0, 50'
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXY
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