Regular expression for a hexadecimal number?

Question

How do I create a regular expression that detects hexadecimal numbers in a text?

For example, ‘0x0f4’, ‘0acdadecf822eeff32aca5830e438cb54aa722e3’, and ‘8BADF00D’.

Answer 1

This one makes sure you have no more than three valid pairs:

(([a-fA-F]|[0-9]){2}){3}

Any more or less than three pairs of valid characters fail to match.