Sample regular expression - Numeric, Decimal, Alphanumeric, Date

Hi all,
Please find useful regular expressions for numeric, alphanumeric, alphabets only, date etc,

1. Numbers only regular expression (0-9 regex) – ^[0-9]*$
2. Decimal numbers with 2 floating point compulsory regular expression (0-9 with decimal) – ^([0-9]*)(\.[0-9]{2})?$
3. Alphabets only regular expression () – ^[a-zA-Z]*$
4. Alphanumeric string regular expression – ^[a-zA-Z0-9]*$
5. Alphanumeric and white space regular expression – ^[a-zA-Z0-9 ]*$
6. Date regular expression (dd/MM/yyyy regex) - ^(((0[1-9]|[12]\\d|3[01])\\/(0[13578]|1[02])\\/((19|[2-9]\\d)\\d{2}))|((0[1-9]|[12]\\d|30)\\/(0[13456789]|1[012])\\/((19|[2-9]\\d)\\d{2}))|((0[1-9]|1\\d|2[0-8])\\/02\\/((19|[2-9]\\d)\\d{2}))|(29\\/02\\/((1[6-9]|[2-9]\\d)(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00))))$