Quickly Replace the Contents of a Text File using C# or VB.NET

In this post, I will show you how to use the File class to quickly replace the contents of a Text File. Check the contents of the Sample.txt file given below.

We will replace the @ with [attherate] and also list the emails one after the other separated by a semicolon(;). Here’s the code to do so:

C#

try
{
    string replaceString = string.Join(";",
                            File.ReadAllLines("D:\\sample.txt")
                            ).Replace("@", "[attherate]");

    File.WriteAllText("D:\\sample.txt", replaceString);
    Console.WriteLine("Done");
    Console.ReadLine();
}
catch (Exception ex)
{
    // handle ex
}

VB.NET

Try
    Dim replaceString As String = String.Join(";", _
        File.ReadAllLines("D:\sample.txt")).Replace("@", "[attherate]")

    File.WriteAllText("D:\sample.txt", replaceString)
    Console.WriteLine("Done")
    Console.ReadLine()
Catch ex As Exception
    ' handle ex
End Try

After running the code, the output is as shown below