Regular expression to convert input in C# - regex

Question

using System;
using System.IO;
class Test
{
public static void Main()
{
try
{
using (StreamReader sr = new StreamReader("TestFile.txt"))
{
String line = sr.ReadToEnd();
Console.WriteLine(line);
}
string pattern1 = #"(in cm)";
string pattern2 = #"mm";
Regex rgx1 = new Regex(pattern1);
Regex rgx2 = new Regex(pattern2);
Regex rgx3 = new Regex(pattern3);
}
catch (Exception e)
{
Console.WriteLine("The file could not be read:");
Console.WriteLine(e.Message);
}
}
}
How to use regular expression in C# to convert the following cm to m from file:
rectangle (in cm) 20 H * 40 W and circle diameter 30 mm

Answer 1

Use like this inside your Main()..
string s1="", s2;
try
{
using (StreamReader sr = new StreamReader("C:\\test.txt")) //in my case
{
s1 = sr.ReadToEnd();
}
}
catch (Exception ei) { MessageBox.Show(ei.Message); }
Console.WriteLine(s1);
Regex r = new Regex(#"\bcm\b"); //regex for changing pattern
s2 = r.Replace(s1, "m");
Console.WriteLine(s2);