如何修复我试图匹配1-100个字母，数字，空格，下划线和短划线的C＃正则表达式

Question

So I have a field

    [RegularExpression(@"([A-Za-z0-9\-\_ ]+){1,100}"]
    public string Name { get; set; }

where the regex is attempting to match strings that are 1-100 characters long and contains only letters, numbers, underscores, dashes and spaces.

I am getting the exception

Additional information: parsing "([A-Za-z0-9-_ ]+){1,100}" - Unrecognized escape sequence _.

How can i fix this?

Answer 1

Try this (get rid of the backslash before the underscore):

[RegularExpression(@"([A-Za-z0-9\-_ ]+){1,100}"]
public string Name { get; set; }

Answer 2

You need to remove all escapes and the + and it is advisable to put the hyphen at the end of the character class to remove any ambiguity:

[RegularExpression("[A-Za-z0-9_ -]{1,100}"]

Since RegularExpressionAttribute pattern is always implicitly anchored, there is no need adding ^ in front and $ at the end. [A-Za-z0-9_ -]{1,100} will match a string that consists of 1 to 100 chars that are either ASCII letters, digits, _ space or - .