using System.IO;

public string GetTempPath()
{
string path = System.Environment.GetEnvironmentVariable("TEMP");
if (!path.EndsWith("\\")) path += "\\";
return path;
}

public void LogMessageToFile(string msg)
{
System.IO.StreamWriter sw = System.IO.File.AppendText(
GetTempPath() + "My Log File.txt");
try
{
string logLine = System.String.Format(
"{0:G}: {1}.", System.DateTime.Now, msg);
sw.WriteLine(logLine);
}
finally
{
sw.Close();
}
}