macOS how to get and set the value in edit text box control?

hi,

I am working a carbon c++ application using XCode in MAC machine.

I have three edit text boxes in my main.nib.

The user will give value in first edit text box.

Based on that value i have to set the value for next two boxes.

How can i set and get a value from the edit text box control in c++?

Thanks in advance and urgent plz..