C++. Please show source code and screenshots. Please use descriptive identifiers (not long variable names) and don't use switch statements. Thank you.

Do you use a calculator? I have a great app on my phone that can either be a simple calculator or perform more advanced work when needed. Your job is to create a program that acts as a calculator. It should allow the user to enter in floating point data and perform basic operators. The program should continually work with a sub-total, adding and subtracting to that value until the user is ready to finish. At that point the grand total will be displayed. Support the following operations: 1. Add a new value to the sub-total 2. Subtract 3. Multiply 4. Divide 5. Add one other feature of your choice