Char array not recognize certain letters

[Keelan]

int main()
{
const int Teachers_Array= 20; //Array Size
const int Student_Array=20; // Array Size

char Teachers_Exam[Teachers_Array] = {'B','D','A','A','C','A','B','A','C','D',
'B','C','D','A','D','C','C','B','D','A'}; // Holds Teachers Answers
char Student_Exam[Student_Array]; // Holds Students Answers


// Introduction and Explanation to the program for the user.
Exam_Intro();

// Answers of Student.
cout<< "Please type in the answers of your student:"<<endl;
// For loop to cycle through all 20 questions
// and put each question in the array element.
for (int count=0; count<Teachers_Array; count++)
{
cout<<"Question #"<<(count+1)<< ". ";
cin>>(Student_Exam [count]);
cin.ignore();

}
// For loop using toupper to cycle through
//each element and make it an uppercase.
for (int x=0; x< Student_Array; x++)
{
Student_Exam[x]= toupper (Student_Exam[x]);
}
return 0;
}



So I think I corrected my toupper problem, but I was now wondering how to make this program not recognize letters other than A, B, C, D. I keep trying to use the while loop for that but I keep getting errors

while( Student_Exam != 'A' && Student_Exam != 'B' etc...) it says that I'm comparing two different types of char

[booradley60]

Student_Exam != 'A' is invalid because Student_Exam is not a character. Student_Exam[0] is a character. So is Student_Exam[1] and so forth...

[Keelan]

Ah, ok. So I'll need another loop that checks each element in the array

Thanks booradley

[booradley60]

Or you could not allow input outside the range a-d like so:
Define a function like this...

bool isValidGrade(char c)
{
    if((c >= 'a' && c <= 'd') ||
       (c >= 'A' && c <= 'D'))
    {
        return true;
    }

    return false;
}

Then change the loop where you get user input to look like this...

for (int count=0; count<Teachers_Array; count++)
    {
        char grade;
        while ((cout<<"Question #"<<(count+1)<< ". ")
            && (!(cin >> grade) || !isValidGrade(grade)))
        {
                std::cout << "That's not a grade between A and D.\n";
                std::cin.clear();
                std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
        }
        std::cin.sync();
        Student_Exam [count] = grade;
    }

[Keelan]

Ah ok Booradley thank you. I should have came back and saw this earlier.
I ended up using:

while( Student_Exam[count] != 'A' && Student_Exam[count] != 'B' && Student_Exam[count]!= 'C' && Student_Exam[count] != 'D')
{
cout<< "Please type in a letter A , B, C, or D."<<endl;
cin>> (Student_Exam[count]);
}

I found out this while loop did work, however last time I was making it wrong and put it in the wrong place in my function.