how can i do program super market cashier in c++?

1) You gather requirements.
2) You design a solution.
3) You write code and when you are stumped on something specific, ask that question here.
4) You test, test, test, and then test some more.
5) You fix your bugs.
6) Repeat steps 4 through 6 a number of times.
7) Modify your code to add new functionality that the customer wants.
8) Repeat Steps 4-6 a bunch more times.
9) Release your solution.