tr translates characters. What you want to do is substitute strings. The strings you want to alter are stored in $line, but your current code, even if tr did as you expected, operates on $_ - the default variable.

The foreach loop "slurps" the file - reads the whole thing into memory. Your current code doesn't require that - use a while loop instead.

The following (untested) code should help:

use strict;
open sourcefile, '<', "source.cbl" or die "Can't open: $!";
open targetfile, '>', "source.ada" or die "Can't open: $!";

while (defined (my $line = <sourcefile>)) {
    if ($line =~ s/WORKING -STORAGE SECTION\./declare;/) {
        print targetfile $line;
    } elsif ($line =~ s/PROGRAM -BEGIN\./begin/) {
        print targetfile $line;
[download]

However there are better ways of doing this trick. For a start you may be better putting your translation pairs into an array then itterate over it for each input line (untested):

use strict;
use warnings;

my @pairs = (
    ['WORKING -STORAGE SECTION.', 'declare'],
    ['PROGRAM -BEGIN.', 'begin;'],
    ['^DISPLAY', 'PUT'],
    ['^ACCEPT', 'GET'],
    ['PROGRAM -DONE.', 'END;'],
    );

open sourcefile, '<', "source.cbl" or die "Can't open: $!";
open targetfile, '>', "source.ada" or die "Can't open: $!";

while (defined (my $line = <sourcefile>)) {
    $line =~ s/$_-[0]/$_->[1]/ for @pairs;
    print targetfile $line;
}
[download]

However this sort of work is really crying out for Parse::RecDescent.

Update change to three parameter opens.

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.