int.TryParse = null if not numeric?

Question

is there some way of return null if it can't parse a string to int?

with:

public .... , string? categoryID) 
{
int.TryParse(categoryID, out categoryID);

getting "cannot convert from 'out string' to 'out int'

what to do?

EDIT:

No longer relevant because of asp.net constraints is the way to solve problem

/M

Answer 1

How about this?

public int? ParseToNull(string categoryId)
{
    int id;
    return int.TryParse(categoryId, out id) ? (int?)id : null;
}