For example, it's not a big deal if the error messages that your code prints are different than ours. The implementation files contain detailed comments at the start of each function skeleton telling you exactly what that function should do. This returns that grand total of all the Holdings values. Each Holding's value is the number of stocks times the current price. If not, return false.
Second argument is negative.
For functions that print output, the comments give examples of the output. If you're still confused, you should be able to student the output of the stocks.exe file and the driver.cpp file to see what some of the operations do. You have 12 small member functions to write for class Holding, and about 5 small and 7 medium-sized functions to write for class Portfolio. Clearly students working in teams should sit down and make some plans at the beginning for to split up this work. You can't write any code until you do that.