ft2str( $feet );
    # Converts $feet to a pretty format
    # (rounding to the nearest 1/16").

    ft2str( $feet, 4 );
    # Rounds to the nearest 1/4" inch instead.

    ft2str( $feet, 1 );
    # Rounds to the nearest inch.

##</code><code>##

use strict;

sub ft2str {
    my $ft= shift(@_);
    my $denom= @_ ? shift(@_) : 16;
    my $numer= int( 0.5 + 12*$denom*$ft );
    my $in= int($numer/$denom);
    $numer -= $denom*$in;
    $ft= int($in/12);
    $in -= 12*$ft;
    if(  $numer  ) {
        until(  $numer % 2  ||  $denom % 2  ) {
            $numer /= 2;
            $denom /= 2;
        }
        $in .= " $numer/$denom"
    }
    return qq($in")   if  ! $ft;
    return qq($ft')   if  ! $in;
    return qq($ft' $in");
}

print ft2str(12.1), "\n";
print ft2str(12.1,8), "\n";
print ft2str(0.01), "\n";
print ft2str(12.05,2), "\n";
print ft2str(12.01,2), "\n";
__END__
Produces:
12' 1 3/16"
12' 1 1/4"
0 1/8"
12' 0 1/2"
12'