Today, using the validation date, I found a regular expression:
((^ (1[8-9]\d{2) | ([2-9]\d{3})) ([-\/\._]) (10|12|0?) [13578]) ([-\/\._]) (3[01]| [12] [0-9]|0? [1-9]) $)| (^ (1[8-9]\d{2}) | ([2-9]\d{3})) ([-\/\._]) (11|0?) [469]) ([-\/\._]) (30| [12] [0-9]|0? [1-9]) $)| (^ (1[8-9]\d{2}) | ([2-9]\d{3})) ([-\/\._]) (0?2) ([-\/\._]) (2[0-8]|1[0-9]|0?) [1-9]) $)| (^ ([2468][048]00) ([-\/\._]) (0?2) ([-\/\._]) (29) $) | (^ ([3579][26]00) ([-\/\._]) (0?2) ([-\/\._]) (29) $) | (^ ([1][89][0][48]) ([-\/\._]) (0?2) ([-\/\._]) (29) $) | (^ ([2-9][0-9][0][48]) ([-\/\._]) (0?2) ([-\/\._]) (29) $) | (^ ([1][89][2468][048]) ([-\/\._]) (0?2) ([-\/\._]) (29) $) | (^ ([2-9][0-9][2468][048]) ([-\/\._]) (0?2) ([-\/\._]) (29) $) | (^ ([1][89][13579][26]) ([-\/\._]) (0?2) ([-\/\._]) (29) $) | (^ ([2-9][0-9][13579][26]) ([-\/\._]) (0?2) ([-\/\._]) (29) $)) "
There is also the addition and subtraction of dates:
DateTime.AddDays (3);//Three days later
DateTime.AddDays (-3);//Three days ago
Regular expression for validating dates