正则表达式匹配的字符串

Question

Im working and a fun project with c# and now I have a problem with my RegEx . I have tried some varitations but didnt found a solution for this. I want a RegEx for this string "##Test1##" .

So I have tried this RegEx here:

[\#]{2}[a-zA-Z0-9]{1,}[\#]{2}

And its working fine but my problem is that,
When passed "###Test1###" the RegEx ignores the first and last # and matches on the inner "##Test1##" .

But I dont want that.

The RegEx only should match to this string ##Test1## .

Hopefully here are some guys who can help me with that problem.
Greetings,

Answer 1

If the regular expression should only match the string you've specified, here's your regular expression:

^##Test1##$

If you want it to match a string like "##(any digit or letter here)##" , then this will work:

^##[a-zA-Z0-9]+##$

This will match strings like

##abc##
##123##

but not

###xxx###     <-- 3 #'s

---

I think the main part you're looking for here are these two symbols:

+------------------- matches the beginning of the string
|                +-- matches the end of the string
v                v
^##[a-zA-Z0-9]+##$

These two will make sure you're not searching to the string to see if your pattern exists inside it, but you're instead checking if the string matches the pattern completely.

Answer 2

This will match the required string when standing alone, and also if it is embedded in a longer character sequence:

[^#]*##[a-zA-Z0-9]+##[^#]*

Hello##World##! -> matches=true
##World##       -> matches=true

Hello##World### -> matches=false
###World###     -> matches=false

Answer 3

Well, thats because is contained inside, so is obviously right. What about with "excluding" characters like at the end/beginning .^#* but obviosly that only works if you want to avoid just that character...