private void date_of_birth_text_TextChanged(object sender, TextChangedEventArgs e) { age_text.Text = ""; if (date_of_birth_text.Text == "") { return; } if (!Regex.Match(date_of_birth_text.Text, @"\d{2}/\d{2}/\d{4}").Success) { return; } if (!_dateOfBirth.testDate(date_of_birth_text.Text)) { MessageBox.Show(Helper_Classes_namespace.ErrorMessages.getErrorMessage()); return; } if (!selectedFromDatgaSet) { dataSet = _dateOfBirth.getDateOfBirth(new List <Amazing_charts_sample_program_Patient_Format>(), getTextBoxData(new Patient())); if (dataSet.Count == 0) { MessageBox.Show(Helper_Classes_namespace.ErrorMessages.getErrorMessage()); return; } createDataSet1(dataSet); } age_text.Text = _dateOfBirth.getAgeByBirthDate(date_of_birth_text.Text); }