How to create a interfaces in c++

Question

for my cellular :т
https://code.sololearn.com/c4aqHl1xmRsD/?ref=app

Answer 1

what do you mean by "interfaces"? The Java feature for classes, or something else?

Answer 2

GUI maybe for calculate

Answer 3

Doggy :3 , it's not gui, but simplest way would be to have third input in the form of char data type..
that input should be second input...if user gives input as 2+5, you add these two numbers... check whether second input of type character is other than +,-,*,/,% display message to user that invalid operator