Some challenges you could try...
1) Create a program that displays various shapes using asterisks. Create a rectangle, right triangle facing left and one facing right, an equilateral triangle and most of all a diamond. Do these with only for loops.
2) Using only a while loop, create a program that asks a user to specify multiple integers and adds them up until it reaches a sentinel value like 9999. Divide this sum by the number of integers that were inputted by the user to get the average. Example the user enters... 4, 3, 2, 3 = 12 / 4 terms = average of 3.
3) With only two for loops, create a bubblesort algorithm that has a fixed number of passes and no longer takes into account values that have already been properly sorted (that is values that have already been bubbled up).
If you need a quick refresh on the format of the various types of loops, you can check out the link below. Enjoy!
C++ and Loops