#!/usr/bin/env perl

use strict;
use warnings;

for my $infile (@ARGV) {
    warn "Processing $infile...\n";
    open my $in, $infile or
        die "Cannot open $infile for reading: $!\n";
    my $s;
    my $changed = 0;
    while (<$in>) {
        $changed += s{//(.*)}{/* $1 */};
        $s .= $_;
    }
    close $in;

    if ($changed) {
        my $outfile = $infile;
        open my $out, ">$outfile" or
            die "Cannot open $outfile for writing: $!\n";
        print $out $s;
        close $out;
        warn "Wrote $outfile\n";
    }
}