Regular Expression in asp.net

This table lists the regular expressions which were used in this sample code, the data type each is intended to recognize, and some examples of strings that each regular expression accepts (matches) and rejects (does not match).

data type	regular expression	accepts	rejects
whitespace	/^\s+$/	spaces, tabs, etc.	0 a
single letter	/^[a-zA-Z]$/	a A	0 . -
alphabetic string	/^[a-zA-Z]+$/	aAbB	a1 23
single digit	/^\d/	0	00 1a
single letter or digit	/^([a-zA-Z]|\d)$/	0 a	00 1a
alphanumeric string	/^[a-zA-Z0-9]+$/	a1b2	2.5 1.a
integer	/^\d+$/	0 23	23.5
signed integer	/^(+|-)?\d+$/	-1 +12	-1.1
floating point number	/^((\d+(\.\d*)?)|((\d*\.)?\d+))$/	1.1 .9 8.	-1.1 .
signed float	/^(((+|-)?\d+(\.\d*)?)|((+|-)?(\d*\.)?\d+))$/	-1.1 1.1 .9 8.	1a
email address	/^.+\@.+\..+$/	a@b.c	a@b