Validating input under while ((input < 'A') || (input > 'D')), get caught in loop. Here is full file.

/********************

Drivers License

********************/

#include

#include

#include

using namespace std;

// Class

class TestGrader

{

char answers[20];

int ans[20];

public:

// Functions

void setKey(char Key[]);

void grade(char Answers[]);

// void numToString(int num[]);

// void numToString(char cString[]);

// void numToString(string num[]);

};

// Member function of setKey

void TestGrader::setKey(char Key[])

{

for (int i = 0; i < 20; i++)

{

if (Key[i] >= 'A'&&Key[i] < 'D')

answers[i] = Key[i];

else

answers[i] = ' ';

}

return;

}

// Member function of grade

void TestGrader::grade(char testAnswer[])

{

int correct = 0;

for (int i = 0; i < 20; i++)

{

if (testAnswer[i] == answers[i] || answers[i] == ' ')

{

correct++;

}

}

// Check answers

if (correct >= 15)

{

cout << " The applicant has passed the exam. ";

}

else

cout << " The applicant has failed the exam. ";

cout << "Number of correct answers: " << correct << endl;

cout << "Number of incorrect answers: " << 20 - correct << endl;

cout << " List of questions with incorrect answers: ";

for (int i = 0; i < 20; i++)

{

if (testAnswer[i] != answers[i] && answers[i] != ' ')

cout << i+1 << " ";

}

}

/***************************************************

// Member funciont of numToString

string TestGrader::numToString(int num[]) const

{

ostringstream ss;

ss << num;

return ss.str();

}

// Member function of numToString

string TestGrader::numToString(int num) const

{

char cString[3];

_itoa_s(num, cString, 10);

string numString(cString);

return numString;

}

// Member functin of numToSTring

string TestGrader::numToString(int num) const

{

string numString = std::to_string(num);

return numString;

}

**************************************************/

int main()

{

// Declare variables

char input, answers[20];

// Define array of answers

char correctAnswers[20] = { 'B', 'D', 'A', 'A', 'C', 'A', 'B', 'A', 'C', 'D',

'B', 'C', 'D', 'A', 'D', 'C', 'C', 'B', 'D', 'A' };

// TestGrader class object

TestGrader Test;

// Call the setKey function

Test.setKey(correctAnswers);

do

{

// Input

cout << "Welcome to Driver's License Exam";

cout<<" There are 20 multiple choice questions ranging from A to D.";

for (int i = 0; i < 20; i++)

{

cout << " Enter an answer to Question " << i + 1 << ": ";

cin >> input;

input = toupper(input);

while ((input < 'A') || (input > 'D'))

{

cout << " Invalid input, try again.";

cout << " Enter an answer to Question " << i + 1 << ": ";

cin >> input;

}

if (input >= 'A' && input <= 'D')

answers[i] = input;

}

// Call the grade function

Test.grade(answers);

// Allow more test

cout << " Do you want to continue?";

cout << " Press Y to continue or Q to quit";

cin >> input;

}while (input != 'Q' && input != 'q');

cin.get();

return 0;

}