Which Radio button in the group is checked

Question

Using WinForms  Is there a better way to find the checked RadioButton for a group  It seems to me that the code below should not be necessary  When you check a different RadioButton then it knows which one to uncheck    so it should know which is checked  How do I pull that information without doing a lot of if statements  or a switch         RadioButton rb   null        if  m RadioButton1 Checked    true                 rb   m RadioButton1              else if  m RadioButton2 Checked    true                 rb   m RadioButton2              else if  m RadioButton3 Checked    true                 rb   m RadioButton3

User · Answer

The GroupBox has a Validated event for this purpose  if you are using WinForms   private void grpBox Validated object sender  EventArgs e                GroupBox g   sender as GroupBox          var a   from RadioButton r in g Controls                  where r Checked    true select r Name          strChecked   a First

User · Answer

The OP wanted to get the checked RadioButton BY GROUP  While  SLaks  answer is excellent  it doesn t really answer the OP s main question  To improve on  SLaks  answer  just take the LINQ one step further   Here s an example from my own working code  Per normal WPF  my RadioButtons are contained in a Grid  named  myGrid   with a bunch of other types of controls  I have two different RadioButton groups in the Grid   To get the checked RadioButton from a particular group   List lt RadioButton gt  radioButtons   myGrid Children OfType lt RadioButton gt    ToList    RadioButton rbTarget   radioButtons        Where r   gt  r GroupName     GroupName   amp  amp  r IsChecked         Single      If your code has the possibility of no RadioButtons being checked  then use SingleOrDefault    If I m not using tri-state buttons  then I always set one button  IsChecked  as a default selection

User · Answer

You could use LINQ   var checkedButton   container Controls OfType lt RadioButton gt                                           FirstOrDefault r   gt  r Checked     Note that this requires that all of the radio buttons be directly in the same container  eg  Panel or Form   and that there is only one group in the container   If that is not the case  you could make List lt RadioButton gt s in your constructor for each group  then write list FirstOrDefault r   gt  r Checked

User · Answer

In addition to the CheckedChangedEvent wiring one could use the Controls  Tag  property to distinguish between the radio buttons    an  spaghetti code  alternative would be the  TabIndex  property  P

User · Answer

You can use the CheckedChanged event for all your RadioButtons  Sender will be the unchecked and checked RadioButtons

User · Answer

You can use an Extension method to iterate the RadioButton s Parent Controls collection  This allows you to query other RadioButtons in the same scope  Using two extension methods  you can use the first determine whether any RadioButtons in the group are selected  then use the second to get the selection  The RadioButton Tag field can be used to hold an Enum to identify each RadioButton in the group       public static int GetRadioSelection this RadioButton rb  int Default   -1            foreach Control c in  rb Parent Controls                RadioButton r   c as RadioButton              if r    null  amp  amp  r Checked  return Int32 Parse  string r Tag                     return Default             public static bool IsRadioSelected this RadioButton rb            foreach Control c in  rb Parent Controls                RadioButton r   c as RadioButton              if r    null  amp  amp  r Checked  return true                    return false          Here s a typical use pattern   if  MyRadioButton IsRadioSelected         MessageBox Show  No radio selected        return    int selection   MyRadioButton GetRadioSelection

User · Answer

Sometimes in situations like this I miss my youth  when Access was my poison of choice  and I could give each radio button in a group its own value   My hack in C  is to use the tag to set the value  and when I make a selection from the group  I read the value of the tag of the selected radiobutton  In this example  directionGroup is the group in which I have four five radio buttons with  None  and  NE    SE    NW  and  SW  as the tags on the other four radiobuttons   I proactively used a button to capture the value of the checked button  because  because assigning one event handler to all of the buttons  CHeckCHanged event causes EACH button to fire  because changing one changes them all  So the value of sender is always the first RadioButton in the group  Instead  I use this method when I need to find out which one is selected  with the values I want to retrieve in the Tag property of each RadioButton     private void ShowSelectedRadioButton                 List lt RadioButton gt  buttons   new List lt RadioButton gt             string selectedTag    No selection           foreach  Control c in directionGroup Controls                        if  c GetType      typeof RadioButton                                 buttons Add  RadioButton c                                   var selectedRb    from rb in buttons where rb Checked    true select rb  FirstOrDefault            if  selectedRb  null                         selectedTag   selectedRb Tag ToString                       FormattableString result     Selected Radio button tag   selectedTag            MessageBox Show result ToString             FYI  I have tested and used this in my work   Joey

User · Answer

Yet another try - Using event lambda expressions As form initializes a single event handler can be assigned to all controls of type RadioButton in a group box  and use  tabIndex or  tag property to identify what option is checked when it changes  This way you can subscribe to any of the events of each radio button in one go int priceOption   0  foreach  RadioButton rbtn in grp PriceOpt Controls OfType lt RadioButton gt           rbtn CheckedChanged     o  e    gt                var button    RadioButton o          if  button Checked                        priceOption   button TabIndex                      As events are assigned to radio buttons only  no type checking of sender is implemented  Also notice as we loop all buttons this could be a perfect moment to assign data properties  change text etc

User · Answer

If you want to get the index of the selected radio button inside a control you can use this method   public static int getCheckedRadioButton Control c        int i      try               Control ControlCollection cc   c Controls          for  i   0  i  lt  cc Count  i                          RadioButton rb   cc i  as RadioButton              if  rb Checked                                return i                                    catch               i   -1            return i      Example use   int index   getCheckedRadioButton panel1     The code isn t that well tested  but it seems the index order is from left to right and from top to bottom  as when reading a text  If no radio button is found  the method returns -1   Update  It turned out my first attempt didn t work if there s no radio button inside the control  I added a try and catch block to fix that  and the method now seems to work

User · Answer

You can wire the CheckedEvents of all the buttons against one handler  There you can easily get the correct Checkbox      Wire all events into this  private void AllCheckBoxes CheckedChanged Object sender  EventArgs e           Check of the raiser of the event is a checked Checkbox         Of course we also need to to cast it first      if    RadioButton sender  Checked               This is the correct control          RadioButton rb    RadioButton sender

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For developers using VB NET    Private Function GetCheckedRadio container  As RadioButton     For Each control In container Children         Dim radio As RadioButton   TryCast control  RadioButton           If radio IsNot Nothing AndAlso radio IsChecked Then             Return radio         End If     Next      Return Nothing End Function

User · Answer

For those without LINQ   RadioButton GetCheckedRadio Control container        foreach  var control in container Controls                RadioButton radio   control as RadioButton           if  radio    null  amp  amp  radio Checked                        return radio                       return null

User · Answer

if you want to save the selection to file or any else and call it later  here what I do  string   lines   new string 1    lines 0     groupBoxTes Controls OfType lt RadioButton gt                 FirstOrDefault r   gt  r Checked  Text   File WriteAllLines  Config ini   lines     then call it with  string   ini   File ReadAllLines  Config ini    groupBoxTes Controls OfType lt RadioButton gt     FirstOrDefault r   gt   r Text    ini 0    Checked   true

[c#] Which Radio button in the group is checked?

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