use strict;
use warnings;

my $dir;
while ( (print "enter directory; "), $dir=<STDIN> and $dir =~ /\\\\|\/\//g)
{
   print "invalid directory syntax... double ", '// or \\\\', " not allowed!\n";
}

$dir =~ s/^\s*|\s*$//g;  #remove leading and trailing spaces
print "INPUT LOOP says $dir\n";

__END__


C:\Monks>perl CommandLoopNoDoubleSlash.pl
enter directory; C:\\x
invalid directory syntax... double // or \\ not allowed!
enter directory; D:\x\temp//
invalid directory syntax... double // or \\ not allowed!
enter directory; C://x
invalid directory syntax... double // or \\ not allowed!
enter directory;     C:/X
INPUT LOOP says C:/X