C＃正则表达式没有空格-字符-下划线

Question

I'm trying to figure out how to filter with regex the following examples

"  test  " -> no
"test" -> yes
"test_test" -> yes
"test123test" -> no

I'v tried to figure it out with the numerous topics on here and the REL reference but I only got absolutely confused and lost!

@"^[^a-zA-Z\s]{2-40}$"
@"^[^\d\s]{2-40}$"

both are letting through white spaces everywhere.

Also I wan to fit in a underscore filter but just _ not every special characters.

help pls and if you could reference me some documentation too it would be grate!

Thanks

Answer 1

If you need to match 2 to 40 symbol string that may contain ASCII letters and _ , use

^[a-zA-Z_]{2,40}$

See the regex demo

C# declaration:

string pat = @"^[a-zA-Z_]{2,40}$";

Details :

• ^ - start of string anchor
• [a-zA-Z_]{2,40} - 2 to 40 (as {2,40} is a limiting quantifier ) chars that are lower- or uppercase ASCII letters or _ symbols (the [...] is a character class construct matching just 1 char)
• $ - end of string anchor