How to overwrite next line after found line in text document

Question

here I want one thing, so I take line from some value, found it in text document and now I want overwrite X not over the found line, but over the next line coming after this found line

so if content is:

line1

line2

line3

line4

and if

string text = "line2";

with this code:

using System;

using System.IO;



namespace _03_0

{

    class Program

    {

        static void Main(string[] args)

        {

            string text = "line2";



            string text = File.ReadAllText("doc.txt"); 

            text = text.Replace(text, "X"); 

            File.WriteAllText("doc.txt", text);          

        }

    }

}

I have this result:

line1

X

line3

line4

but I want this result:

line1

line2 

X

line4

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Answer 1

I suggest using Regular Expressions for this:

string filePath = @"doc.txt";
string myStr = "line2";
string content = File.ReadAllText(filePath);
string pattern = string.Format(@"(?<={0}\r\n).+?(?=\r\n)", myStr);
Regex r = new Regex(pattern);
File.WriteAllText(filePath, r.Replace(content, "X"));

P.S: you'll need to import RegularExpressions namespace:

using System.Text.RegularExpressions;

Hope that helps :)

A side note: You can't use the same variable name (text) twice.

How to overwrite next line after found line in text document

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