Range comparisons are practically unknown among programming languages. As far as I know, Perl 6 will be the first widely used language to allow range checking.

Older languages use the excuse of implementation to forbid something which is a natural mathematical statement. Comparisons like < return a boolean value, a truth value: Is 9 less than $X? yes or no?. Languages such as C would then use the result of that comprison in stage two: Is (9<$X) less than 100?. Obviously unlikely to be what you want, so Perl detects and reports the error.

By optimizing your comparisons a little, you can eliminate the need for range testing:

if ( $X < 0 ) {
    handle_X_under_0();
} elsif ( $x < 10 ) {
    $Y = $X + 2000;
} elsif ( $X < 100 ) {
    $Y = $X + 1900;
} else {
    handle_X_over_100();
}
[download]