asp.net - Possible to add a class to an existing class attribute of object via C#? -

I have an existing class for an input, is it possible to add an additional class for the object in C # .net Instead, one / the second should not have a preset class on the first place in the first place?

  txtField.CssClass = "first-class"; // Output: class = "first class" txtField.CssClass + = "another_class"; // output: class = "first_clos other_ class"