C#

var textReader = new StreamReader(path + "\\web.config");
var fileContents = textReader.ReadToEnd();
if (fileContents.IndexOf(oldPwd, StringComparison.Ordinal) == -1)
{
    Log("Old Password Not Found.", 0);
}
else
{
    Log("Replacing old password", 1);
    fileContents = fileContents.Replace(oldPwd, newPwd);
}

var mystring = "this is a password 123^ yeah";
Console.WriteLine("Did it find it: " + mystring.IndexOf("123^", StringComparison.Ordinal).ToString());
Console.WriteLine("Did it replace it: " + mystring.Replace("123^", "456"));
mystring = "this is a password 123^456 yeah";
Console.WriteLine("Did it find it: " + mystring.IndexOf("123^456", StringComparison.Ordinal).ToString());
Console.WriteLine("Did it replace it: " + mystring.Replace("123^456", "abcdefg"));

string strDate = _dataset.Table["table"].Rows[0]["field_date"].ToString();

_dateset.Tables["table"].Rows[0]["field_date"] = DateTime.ParseExact(strDate, "dd/MM/yyyy", CultureInfo.CurrentCulture);