C#

class App {
  internal void Run() {
    String[] tests = new String[] {"aAa!", "aardvark", "Aardvark", "AARDVARK",
      "0123456789", "0123456789a"};
    foreach (String s in tests) {
      TestRegex(s);
    }
  }

  private static void TestRegex(String test) {
    String expr = "[^A-Z0-9]+"; // one or more match of any char except
    Regex rgxTest = new Regex(expr);
    Boolean result = !rgxTest.IsMatch(test);  // invert the result
    Console.WriteLine("String {0}\nExpr {1}\nResult {2}\n", test, expr, result);
  }

monu_khan wrote:

actually can i store image in database and compare them
but it does not work

Bitmap bitmap = new Bitmap(1, 1);
string fullPath = string.Format(
    "{0}\\bitmap.bmp",
    Environment.GetFolderPath(Environment.SpecialFolder.MyPictures));
bitmap.Save(fullPath);