regex to remove ordinals

Question

I need to remove ordinals via regex, but my regex skills are quite lacking. The following locates the ordinals, but includes the digit just prior in the return value. I need

Answer 1

In perl:

$var =~ s{\b(\d+)(?:st|nd|rd|th)\b}{$1};

In PHP:

$var = preg_replace('/\\b(\d+)(?:st|nd|rd|th)\\b/', '$1', $var);

In .NET:

var = Regex.Replace(@"\b(\d+)(?:st|nd|rd|th)\b", "$1");