For your if statement take a look at substr and index.

$foo =~ s/\s/\\g;

The code above is not working, what would work is: $foo =~ s/\s//g; # not efficient which substitutes every whitespace (\s, i.e. space, tab, newline, ...) with nothing. Thus every whitespace is deleted. But I don't see how that could help you for your problem.

For your replacements you should look at the tr/// operator.

-- Hofmator