You can't do this:
if ((menuItem >= 'A' || 'a') && (menuItem <= 'C' || 'c'))
(Well you can, but the results aren't going to be what you expect.)
You have to write out each expression:
if ((menuItem >= 'A' || menuItem <= 'a') && (menuItem <= 'C' || menuItem <= 'c'))
while (number != SENTINEL)
{ // open while 3
counter++;
cin >> number;
{ // why do you have these braces
cin >> number; // you already did a cin above ^_^
if (number < temp2) // temp2 has never been initalized in this section!
// how I would do it is set temp2 to -99, and then do the following if:
// if (number < temp2 || temp2 == -99) { ...
temp2 = number;
} // you really don't need them
}
Also, the way you're doing that loop, -99 is registered as the "lowest number" because it only bales out after it's done the comparison with
temp2.
Not unnormal (you don't really need to worry about this), but when you input especially large numbers, it throws the program into an endless loop that has to be manually terminated.
[edit]By the way, in the menu loop, you need to somewhere reset your variables, because otherwise if you try to run section B twice, for example, you'll find that it doesn't allow input -- it just jumps right to the final output.
[/edit]