Infact I want to read from one file and convert data read and after it i write it in another file

FileInfo theSourceFile = new FileInfo(@"C:\WindowsFormsApplication1.txt");
StreamWriter str1 = new StreamWriter(@"C:\WindowsFormsApplication2.txt", false);
StreamReader stream = theSourceFile.OpenText();
string sline;
while ((sline = stream.ReadLine()) != null)
{
    string hex = "";
    foreach (char c in sline)
    {
        int tmp = c;
        hex += String.Format("{0:x2}", (uint)System.Convert.ToUInt32(tmp.ToString()));
    }

    str1.WriteLine(hex);
    str1.Close();

}
stream.Close();