Compute the total value of the orders in the two files from the previous exercise. The value of an individual Purchase is (of course) its unit_price*count.

Data from Previous Exercise

Define an Order class with (customer) name, address, data, and vector members. Purchase is a class with a (product) name, unit_price, and count members. Define a mechanism for reading and writing Orders to and from a file. Define a mechanism for printing Orders. Create a file of at least ten Orders, read it into a vector, sort it by name (of customer), and write it back out to a file. Create another file of at least ten Orders of which about a third are the same as in the first file, read it into a list, sort it by address (of customer), and write it back out to a file. Merge the two files into a third using std::merge().