06 implement the four-digit provisioner for determining the decimal point input location, and the four-digit decimal point operation

06 implement the four-digit provisioner for determining the decimal point input location, and the four-digit decimal point operation

1 private void txtnumberw.keypress (object sender, KeyPressEventArgs e) 2 {3 // MessageBox. show (int) (e. keyChar )). toString (); // ASCii View 4 // This event may be triggered by multiple text boxes, therefore, use sender to obtain the control 5 TextBox currentTextBox = sender as TextBox; 6 7 if (e. keyChar <'0' | e. keyChar> '9') 8 {9 e. handled = true; 10} 11 if (e. keyChar = 46) // you can enter the decimal point 12 {13 // check whether the number1 text box contains the decimal point 14 if (currentTextBox. text. indexOf (". ") =-1) 15 {16 // The cursor cannot be in the first place, that is, the decimal point cannot appear in the first 17 if (currentTextBox. selectionStart> 0) 18 {19 e. handled = false; 20} 21} 22} 23 if (e. keyChar = 8) // enables the user to enter the backspace key 24 {25 e. handled = false; 26} 27 28} 29 30 private void btnResult_Click (object sender, EventArgs e) 31 {32 try33 {34 double number1 = Convert. toDouble (txtNumber1.Text); 35 double number2 = Convert. toDouble (txtNumber2.Text); 36 37 switch (comboBox1.Text) 38 {39 case "plus": 40 lbResult. text = (number1 + number2 ). toString (); 41 break; 42 case "minus": 43 lbResult. text = (number1-number2 ). toString (); 44 break; 45 case "multiplication": 46 lbResult. text = (number1 * number2 ). toString (); 47 break; 48 case "except": 49 lbResult. text = (number1/number2 ). toString (); 50 break; 51} 52} 53 catch (Exception ex) 54 {55 MessageBox. show ("your input is incorrect" + ex. message); 56} 57} 58 59 private void txtNumber1_TextChanged (object sender, EventArgs e) 60 {61 lbResult. text = ""; 62} 63 64 private void frmFourOperations_Load (object sender, EventArgs e) 65 {66 comboBox1.SelectedIndex = 0; // when the dropdownstyle attribute of combobox is set to list, the initial value cannot be written to the attribute. You need to use this statement to implement 67}