c# - 创建一个 RegEx 来验证用户名

Question

我编写这段代码来验证用户名是否满足给定条件，有人看到我如何将 2 个 RegEx 合并为一个吗？代码是c#

    /// <summary>
    /// Determines whether the username meets conditions.
    /// Username conditions:
    /// Must be 1 to 24 character in length
    /// Must start with letter a-zA-Z
    /// May contain letters, numbers or '.','-' or '_'
    /// Must not end in '.','-','._' or '-_' 
    /// </summary>
    /// <param name="userName">proposed username</param>
    /// <returns>True if the username is valid</returns>
    private static Regex sUserNameAllowedRegEx = new Regex(@"^[a-zA-Z]{1}[a-zA-Z0-9\._\-]{0,23}[^.-]$", RegexOptions.Compiled);
    private static Regex sUserNameIllegalEndingRegEx = new Regex(@"(\.|\-|\._|\-_)$", RegexOptions.Compiled);
    public static bool IsUserNameAllowed(string userName)
    {
        if (string.IsNullOrEmpty(userName)
            || !sUserNameAllowedRegEx.IsMatch(userName)
            || sUserNameIllegalEndingRegEx.IsMatch(userName)
            || ProfanityFilter.IsOffensive(userName))
        {
            return false;
        }
        return true;
    }

Answer 1

如果我正确理解您的要求，下面应该是您想要的。 \w匹配字母、数字或 _ .

negative lookbehind ((?<![-.]) 部分)允许 _除非前面的字符是 .或 - .

@"^(?=[a-zA-Z])[-\w.]{0,23}([a-zA-Z\d]|(?<![-.])_)$"