C++ :: Comparing Multiple Constant Char At Once?

I have an array of const char's that are randomly selected in a loop from a list and id like to compare every newly selected choice to be tested against all the others to make sure the same choice isn't given more than once, however the names are lengthy and, for example, using:

for (int x = 0; x<10;x++)//initial loop
while ((choice[x]== choice[x-1] || (choice[x] == choice[x-2]) || etc...)
//^given that I have 10 variables

Would be messy and a painful sight. What would a more convinient way to check each choice?

Edit:It should be said that each choice would then be randomized again and then checked again, and that each newly selected choice is then immediantly used after this. It'll also be assumed that not all the choices have been made when this part runs(ergo choice[3] may not exist yet) as it is in a loop