i want to search for a ".c" file or ".h" file in a dir.so, i just took an example. this piece of code is giving unexpected output can you tell where it is going wrong

$tu ="D:\\vroom\\diags\\in\\frameworks\\my_ip\\shock.h";
print "res:\t$res\n" if $res=$tu=~ m/$.c/g;
print "res:\t$res\n" if $mes=$tu=~ m/$.h/g;
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this pice of code returning true for even the first case. it is just searching for "c" not ".c". what should i do to make it search for ".c". where can i check wether i received an answer to my post ?

$tu ="D:\\vroom\\diags\\in\\frameworks\\my_ip\\shock.h";

if ($mes=$tu=~ m/$.h/g)
{
    open FH, $tu or die "cannot open D:\\vroom\\diags\\in\\frameworks\
+\my_ip\\shock.h :$!\n";
    while ( my $line = <FH>)
    {
        $line =~ s/\\t/    /g;
    }
close (FH) or die "cannot close D:\\vroom\\diags\\in\\frameworks\\my_i
+p\\shock.h:$!\n";
}
else
{
    print "out of loop\n";
}
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Above code snippet is not substituting \t(tab) with four space. what should i do achieve it ? How do i get intimated wether i received an answer to my post ?????? THANKS,