Read the names of twenty objects (such as "cat", "chair", etc.) from a file into a std: : set<string> container one by one. Display each object in the console window scrolling the screen up by five lines between each object and allowing an interval of half a second between each line scroll (fgw: :Wait (500); will provide a half second pause). Continue scrolling after the last object until the console is blank. Ask the user to type in the names of the objects. Remove each correct answer from the container. Allow two minutes for their answers. At the end, print a list of any remaining items.
For this exercise you will need the clock $\mathrm{O}$ function that is declared in the ectimes header. It returns a value that depends on how long a program has been running. The return type is clock_t and, for MinGW, it measures time in thousandths of a second. So the following statement outputs the time the program has been running, in thousandths of a second:
cout $\ll$ clockO $\ll{ }^{\prime} \backslash n '$;
The following statement saves the program time in the variable called start:
clock_t const start(clock $\mathrm{O})$;
Do not confuse this with facilities you may read about to extract and manage calendar time. clockO is entirely to do with measuring time since program start.
There are many ways that you can polish this program. You could store the user's answers in another container and display them at the end. You could tell them when they have got one right (one way to detect that is by checking the return value of erase $\mathrm{O}$ which will be true if an element was removed).
Keep the objects simple so that typing errors are not going to be a problem.