linqPad demo of c# Regex extension method to replace tokens in a string using a token / value dictionary

replaceTokens.linq

<Query Kind="Program" />

// define regex to match $-delimited tokens, eg $name$
static Regex toke = new Regex(@"\$(\w+)\$", RegexOptions.Compiled);

static void Main() 
{
    string input = @"Dear $name$, as of $date$ your balance is $amount$";
	var args = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
	args.Add("name", "Mr Smith");
	args.Add("date", "05 Aug 2009");
	args.Add("amount", "£200");

	string output = toke.replaceTokens(input, args);
	output.Dump();
}

public static class ReplaceTokensUsingDictionary
{
	public static string replaceTokens(this Regex re, string input, IDictionary<string, string> args)
	{
		return re.Replace(input, match => args[match.Groups[1].Value]);
	}
}