It is unclear what you are trying to achieve.
But first off, do not ever mix char arrays and std::cin >>. Use std::string instead of char arrays.
So, what do you want to accomplish? Do you want to see if your inputted strings consists of one or more of the not valid input characters?
If so, then this should do what you want:
Code:
std::string input;
const std::array<char> notValid({'A','B','C'}); // Requires a recent C++11 compiler.
const char notValid[] = { 'A', 'B', 'C' }; // Use this if the above does not compile
...
std::cin >> input;
...
if (std::find_first_of(input.begin(), input.end(), notValid.begin(), notValid.end()) != input.end()) // Use if your compiler supports C++11
if (std::find_first_of( input.begin(), input.end(), notValid, notValid + (sizeof(notValid) / sizeof(notValid[0])) ) != input.end()) // Use if you compiler does NOT support C++11
{
// One or more characters in notValid was found in input.
}