How to Enable One Check Box While Disabling the Others

• Microsoft Visual FoxPro for Windows, version 3.0

SUMMARY

Multiple check boxes are often necessary to gather required input. Frequently, it is desirable to disable the unselected check boxes after the first check box is selected. The example in this article illustrates how to disable the unselected check boxes in a form.

Although option (also known as radio) buttons are generally the preferred of allowing users to make only once choice among a group of choices, this article provides an alternative method of doing so using check boxes.

MORE INFORMATION

The form created by the following example contains three check boxes. When a check box is selected, its Value property is set to 1. After checking the Value property in the Click event of each individual check box, the Enabled properties of the remaining check boxes are changed to false (.F.). Changing these properties disables the check boxes.

Step-by-Step Example

1. Create a new form, and name it Test.scx.

2. Place three check boxes on the form by using the Form Builder.

3. In the Refresh event of the form, place the following code:

   IF ThisForm.Check1.Enabled=.t. and ThisForm.Check1.Value=1

          ThisForm.Check2.Enabled=.f.
          ThisForm.Check3.Enabled=.f.
   

   ENDIF

   IF ThisForm.Check2.Enabled=.t. and ThisForm.Check2.Value=1

           ThisForm.Check1.Enabled=.f.
           ThisForm.Check3.Enabled=.f.
      ENDIF
   
      IF ThisForm.Check3.Enabled=.t. and ThisForm.Check3.Value=1
           ThisForm.Check1.Enabled=.f.
           ThisForm.Check2.Enabled=.f.
      ENDIF
   
      IF ThisForm.Check1.Enabled=.t. and ThisForm.Check1.Value=0
          ThisForm.Check2.Enabled=.t.
          ThisForm.Check3.Enabled=.t.
      ENDIF
   
      IF ThisForm.Check2.Enabled=.t. and ThisForm.Check2.Value=0
          ThisForm.Check1.Enabled=.t.
          ThisForm.Check3.Enabled=.t.
      ENDIF
   
      IF ThisForm.Check3.Enabled=.t. and ThisForm.Check3.Value=0
          ThisForm.Check1.Enabled=.t.
          ThisForm.Check2.Enabled=.t.
      ENDIF
   
   

4. In the InteractiveChange event of each check box, add the following line of code:

   ThisForm.Refresh

5. If you want the disabled check boxes to appear in a different color, set the DisabledBackColor property for each box. The box will automatically change color when disabled.

6. Save and run the form.

7. Click any check box to select it, and the remaining check boxes are disabled. Click the check box a second time to clear it, and the other check boxes are reenabled.

Additional Notes

• Changing the BackColor property to gray emulates a disabled check box in FoxPro 2.x for Windows.
• Typing "Help Backcolor" (without the quotation marks) in the Command window provides a list of colors and their corresponding numbers.

REFERENCES

For more information about Disabling check boxes in FoxPro 2.x, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q111918
   TITLE     : How to Enable One Check Box While Disabling the Others