.NET正则表达式

Question

I need a regular expression for some arguments that must match on a string.

here it is...

1. The string exists out of minimum 8 en maximum 20 characters.

2. These characters of this string may be characters of the alfabet or special chars --With other words..all charachters except from the whitespaces

3. In the complete string there must be atleast 1 number.

4. The string cannot start with a number or an underscore

5. The last 2 characters of the string must be identical, But it doenst matter if those last --identical characters are capital or non-capital (case insensitive)

Must match all :

+234567899
a_1de*Gg
xy1Me*__
!41deF_hij2lMnopq3ss
C234567890123$^67800
*5555555
sDF564zer""
!!!!!!!!!4!!!!!!!!!!
abcdefghijklmnopq9ss

May not match :

Cannot be less then 8 or more then 20 chars:

a_1+Eff
B41def_hIJ2lmnopq3stt

Cannot contain a whitespace:

A_4 e*gg
b41def_Hij2l nopq3ss

Cannot start with a number or an underscore: __1+Eff 841DEf_hij2lmnopq3stt

cannot end on 2 diffrent characters:

a_1+eFg
b41DEf_hij2lmnopq3st

Cannot be without a number in the string:

abCDefghijklmnopqrss
abcdef+++dF
!!!!!!!!!!!!!!!!!!!!
------------------------------------------------------

This is what I have so far...But I'm really breaking my head on this... If you Don't know the answer completely it's not a problem... I just want to get in the right direction

([^0-9_])(?=.*\d)(\S{8,20})(?i:[\S])\1

Answer 1

If you can use multiple regexes, try these:

\S{8,20}

[^_0-9].*\d.*

.*(?i)(.)\1

If it must be one, use this:

^[^_\s\d](?=.*\d)\S{5,17}(?i)(\S)\1$

(I must give Casmir credit for helping me find a bug in this last one.)

EDIT:

This is

1. any one character, other than an underscore, space, or digit.

2. (which must be followed by any characters and then a digit)

3. then five to seventeen non-whitespace characters

4. then (case-insensitive from now on), a whitespace character, followed by the same character

Answer 2

您可以尝试以下方法：

^[^\s\d_](?=.*\d)\S{5,17}(?i)(\S)\1$