The first step in adding a dialog box to your MFC application is creating the dialog box resource, which acts as a sort of template for Windows. When Windows sees the dialog box resource in your program, it uses the commands in the resource to construct the dialog box for you.

In this unit you learn to work with dialog boxes by adding one to a simple application. Create an SDI application just as you did in Lesson 1, "Building Your First Windows Application," calling it simply SDI. You will create a dialog box resource and a dialog box class for the application, write code to display the dialog box, and write code to use the values entered by the user.

To create a dialog box resource, first open the application. Choose Insert, Resource from Developer Studio’s menu bar. The Insert Resource dialog box, shown in Figure 2.1, appears. Double-click Dialog in the Resource Type box. The dialog box editor appears, as shown in Figure 2.2.

Bring up the Properties dialog box for the new dialog box by choosing View, Properties. Change the caption to Sample Dialog, as shown in Figure 2.3. You’ll be using the Properties dialog box quite a lot as you work on this dialog box resource, so pin it to the screen by clicking the pushpin in the upper-left corner.

FIG. 2.1 Double-click Dialog on the Insert Resource dialog box.

FIG 2.2 A brand new dialog box resource has a title, an OK button, and a Cancel button.

FIG. 2.3 Use the Dialog Properties dialog box to change the title of the new dialog box.

The control palette shown to the just adjacaent to the dialog box in Figure 2.2 is used to add controls to the dialog box resource. Dialog boxes are built and changed with a very visual WYSIWYG interface. If you need a button on your dialog box, you grab one from the control palette, drop it where you want it, and change the caption from Button1 to Lookup, or Connect, or whatever you want the button to read. All the familiar Windows controls are available for your dialog boxes:

The sample application in this unit is going to have a dialog box with a selection of controls on it, to demonstrate the way they are used.

Because dialog boxes are often unique to an application (with the exception of the common dialog boxes), you almost always create your own IDs for both the dialog box and the controls it contains. You can, if you want, accept the default IDs that the dialog box editor creates for you. However, these IDs are generic (for example, IDD_DIALOG1, IDC_EDIT1, IDC_RADIO1, and so on), so you’ll probably want to change them to something more specific. In any case, as you can tell from the default IDs, a dialog box’s ID usually begins with the prefix IDD, and control IDs usually begin with the prefix IDC. You change these IDs in the Properties dialog box: Click the control (or the dialog box background to select the entire background), and choose View, Properties unless the Properties dialog box is already pinned in place; then change the resource ID to a descriptive name that starts with IDD for a dialog and IDC for a control.

Click the Edit box button on the control palette, and then click in the upper-left corner of the dialog box to place the edit box. If necessary, grab a moving handle and move it until it is in approximately the same place as the edit box in Figure 2.4. Normally, you would change the ID from Edit1, but for this sample leave it unchanged.

FIG. 2.4 You can build a simple dialog box quickly in the resource editor.

Add a check box and three radio buttons to the dialog box so that it resembles Figure 2.4. Change the captions on the radio buttons to One, Two, and Three. To align all these controls, click one, and then while holding down the Ctrl key, click each of the rest of them. Choose Layout, Align, Left, and if necessary drag the stack of controls over with the mouse while they are all selected. Then choose Layout, Space Evenly, Down, to adjust the vertical spacing.

Click the One radio button again and bring up the Properties dialog box. Select the Group check box. This indicates that this is the first of a group of buttons. When you select a radio button, all the other buttons in the group are deselected.

Add a list box to the dialog box, to the right of the radio buttons, and resize it to match Figure 2.4. With the list box highlighted, choose View, Properties to bring up the Properties dialog box if it is not still pinned in place. Select the Styles tab and make sure that the Sort box is not selected. When this box is selected, the strings in your list box are automatically presented in alphabetical order. For this application, they should be presented in the order that they are added.