display data present struct to richtextbox

Question

I have a comboBox with 3 items in it. I would like display data present in the struct when i select any item.

 

example in comboBox i have circle, triangle, rectangle

 

in a header file I have three struct that contain for

 

circle { radius, circumference.}

 

triangle {sides, area }etc

 

so when i select circle in comboBox I want radius and circumference to be displayed in richtextbox.

 

Can anyone guide me how to do in c++