WPF Checkbox check IsChecked

Multiple answers already but here is another alternative

if (chkRevLoop.IsChecked.GetValueOrDefault()) {}

From MSDN

You can use null coalescing operator. This operator returns right-hand operand if the left-hand operand is null. So you can return false when the CheckBox is in indeterminate state (when the value of IsChecked property is set to null):

if (chkRevLoop.IsChecked ?? false)
{

}

You have to do this conversion from bool? to bool, to make it work:

if((bool)(chkRevLoop.IsChecked)){}

Since it is already a bool condition you need not to put true false because if it is true then only it will come inside this if condition else not. so, no need to even put chkRevLoop.IsChecked == true here, you are by default asking ==true by puttin IsChecked