C#regex在匹配的字符串后查找并删除文本

你可以用

Regex.Replace(s, "(From:).*", "$1 \"redacted\"")

To: ,

Regex.Replace(s, @"\b((?:From|To):).*", "$1 \"redacted\"")

• \b -字界
• ((?:From|To):) -捕获组1:任意一个 From 或 To :
• .* -尽可能多地使用除linebreak字符以外的任何0个或多个字符。

C# demo

var s = "From: Tom novy <AJames@onmicrosoft.com>\nTo: \"mithrandir@wttom.onmicrosoft.com\"\nFrom: David Cusack <AJames@onmicrosoft.com>";
Console.WriteLine(Regex.Replace(s, "(From:).*", "$1 \"redacted\""));

From: "redacted"
To: "mithrandir@wttom.onmicrosoft.com"
From: "redacted"

请注意 (From:).* From: 第1组和 $1 backreference是在替换时将此值放回结果中。

注意 . 在.NET正则表达式中也匹配CR符号,因此如果您计划只替换以CRLF结尾的字符,则需要替换 . 在正则表达式中 [^\r\n]

另外,如果 只有在 ,你需要在它前面加上 ^ RegexOptions.Multiline 修饰符,或 (?m) 内联修饰符, "(?m)^(From:)[^\r\n]*" .

([a-z]+:)(.*?)([a-z]+:)(.*)
(From:)(.*?)(To:)(.*)
(From:)(.*?)([a-z]+:)(.*)

我们会用,

\1 "redacted"\n\3 "redacted"

Please see the demo here for explanation.

试验

using System;
using System.Text.RegularExpressions;

public class Example
{
    public static void Main()
    {
        string pattern = @"([a-z]+:)(.*?)([a-z]+:)(.*)";
        string substitution = @"\1 ""redacted""\n\3 ""redacted""";
        string input = @"From: Tom novy <AJames@onmicrosoft.com>
To: ""mithrandir@wttom.onmicrosoft.com""";
        RegexOptions options = RegexOptions.Singleline | RegexOptions.IgnoreCase;

        Regex regex = new Regex(pattern, options);
        string result = regex.Replace(input, substitution);
    }
}

怎么样

Regex.Replace("From: Tom", @"From\:.*", "From: redacted")