Question

I’m using this code to check that a student number being entered is the correct number of digits. Is there a function like .length() that will work for the variable type double? Thanks!

do {
    cout << "Student's number: (Numeric only)";
    cin >> studentNumber;
    cin.ignore();
}
while (studentNumber.length() != 6);

Answer 1

Read it as text, validate it, then parse it:

std::string input;
bool valid = false;
while (!valid) {
    cout << "Student's number: (Numeric only)";
    cin >> input;
    if (input.size() == 6)
        valid = true;
}
double studentNumber = strtod(input.c_str());