我有一个正则表达式用于验证字符串。但现在我想删除所有与我的正则表达式不匹配的字符。
例如：
regExpression = @"^([\w\'\-\+])"
text = "This is a sample text with some invalid characters -+%&()=?";
//Remove characters that do not match regExp.
result = "This is a sample text with some invalid characters -+";
有什么想法可以使用正则表达式来确定有效字符并删除所有其他字符。
非常感谢
我相信你可以一行代码实现此功能（允许某些字符，替换其余字符）：
var result = Regex.Replace(text, @"[^\w\s\-\+]", "");
从技术上讲，它将生成以下内容： "This is a sample text with some invalid characters - +" 这与您的示例略有不同（在-和+之间多了一个额外的空格）。
就是这么简单：
var match = Regex.Match(text, regExpression);
string result = "";
if(match.Success)
result = match.Value;
删除不匹配的字符等同于保留匹配的字符。这就是我们在这里所做的。
如果你的文本中可能存在多次匹配表达式的情况，你可以使用以下方法：
var result = Regex.Matches(text, regExpression).Cast<Match>()
.Aggregate("", (s, e) => s + e.Value, s => s);
Cast<Match>()中出现错误。我应该用其他东西替换那部分还是按照你输入的代码使用它。谢谢。 - tif /// <summary>
/// Replaces not expected characters.
/// </summary>
/// <param name="text"> The text.</param>
/// <param name="allowedPattern"> The allowed pattern in Regex format, expect them wrapped in brackets</param>
/// <param name="replacement"> The replacement.</param>
/// <returns></returns>
/// // https://dev59.com/C2855IYBdhLWcg3wPBtx
//https://dev59.com/UG025IYBdhLWcg3wNC92
//[^ ] at the start of a character class negates it - it matches characters not in the class.
//Replace/Remove characters that do not match the Regular Expression
static public string ReplaceNotExpectedCharacters( this string text, string allowedPattern,string replacement )
{
allowedPattern = allowedPattern.StripBrackets( "[", "]" );
//[^ ] at the start of a character class negates it - it matches characters not in the class.
var result = Regex .Replace(text, @"[^" + allowedPattern + "]", replacement);
return result;
}
static public string RemoveNonAlphanumericCharacters( this string text)
{
var result = text.ReplaceNotExpectedCharacters(NonAlphaNumericCharacters, "" );
return result;
}
public const string NonAlphaNumericCharacters = "[a-zA-Z0-9]";
这里使用了我 StringHelper 类中的几个函数 http://geekswithblogs.net/mnf/archive/2006/07/13/84942.aspx。
/// <summary>
/// ‘StripBrackets checks that starts from sStart and ends with sEnd (case sensitive).
/// ‘If yes, than removes sStart and sEnd.
/// ‘Otherwise returns full string unchanges
/// ‘See also MidBetween
/// </summary>
public static string StripBrackets( this string str, string sStart, string sEnd)
{
if (CheckBrackets(str, sStart, sEnd))
{
str = str.Substring(sStart.Length, (str.Length – sStart.Length) – sEnd.Length);
}
return str;
}
public static bool CheckBrackets( string str, string sStart, string sEnd)
{
bool flag1 = (str != null ) && (str.StartsWith(sStart) && str.EndsWith(sEnd));
return flag1;
}
var result = Regex.Replace(text, @"[^\w]", m => "%&=?()".Contains(m.Value) ? "" : m.Value);您可以用任何代码替换我的MatchEvaluator来确定是否保留字符。 - emfurry