Stream read help

[orangelight]

I want to make I thing where this program takes a .txt and replaces letter with numbes. I know how to do this with a text box (.replace) but how to I do it to a txt file

[Erendar]

Read your file with File.ReadAllText(string path) and then you can do FileWriteAllText(string path, string content)

[zoneout83]

This would be better

using System;
using System.IO;

class Program
{
    static void Main()
    {
	//
	// It will free resources on its own.
	//
	string line;
	using (StreamReader reader = new StreamReader("file.txt"))
	{
	    line = reader.ReadLine();
	}
	Console.WriteLine(line);
    }
}