A checkbook is a container that holds a record of all the checks written by the owner. Our container, being computerized, offers the user a variety of extra features so that they can find, organize, and better understand their check-based spending.
In Check::write_check, I don't think you want a do-while loop there. That kind of loop always executes the code inside it once so the program tells me my amount was bad but then uses it anyway. Just a while loop there would be appropriate. This also caused a quirky problem since I was running the program using an input file for the additional checks I added so it ran the ins >> amount line again and that messed up the average calculation because it read in my next command as the amount.