#!/usr/bin/perl

use strict;

use constant {
    MIF_EXTENSION => "\.mif",
    TXT_EXTENSION => "\.txt"
};

my $s0 = 'abcd.txt';
print "s0 =\t$s0\n";
$s0 =~ s/\.txt/\.mif/;
print "s0 =\t$s0\n";

my $s1 = 'efgh.txt';
print "s1 =\t$s1\n";
$s1 =~ s/TXT_EXTENSION/MIF_EXTENSION/;
print "s1 =\t$s1\n";