Extract an specific count of chars with cin.get and make sure is correct

Question

I want to extract 6 chars (including '\n') from input to an array and ensure that the input is correct by getting the new line character at an specific place in the array. This is what I did but I cant fix it. If the user enters more than 5 characters the loop repeats but the remaining characters still are in the stream. With the cin.ignore('\n') I get an infinite loop with no character in the stream.

do
{
    cout << "Please log in: \n";
    cin.get(username, 6);
    cin.ignore('\n'); 
    if (username[5] != '\n')
        cout << "\nYour username should be 5 digits!\n\n";
} while (username[5] != '\n');

I don't understand, you want to get 6 chars including "\n" but you are using cin.ignore('\n') ?? — T-D, Nov 22 '13 at 14:08
If you're using C++ why not using std::string rather than char[] ? — Chris L, Nov 22 '13 at 14:09

score 2 · Answer 1 · answered Nov 22 '13 at 14:15

Unless you really want to do character-by-character entry, consider using a string and then making sure your input is valid. That would simplify the code a lot and make it easier to maintain:

string username;

if (cin >> username) {
    if (username.length() != 5) {
        // report bad input
    }
}

score 1 · Answer 2 · answered Nov 22 '13 at 14:14

What you are trying to do can be done much easier using strings, it is simply like this :

string username = "";
do
{
    cout << "Please log in: \n";
    cin>>username ; 
    if (username.length() != 5)
        cout << "\nYour username should be 5 digits!\n\n";
} while (username.length() != 5);

but don't forget to add #include<string> to your code

Extract an specific count of chars with cin.get and make sure is correct

2 Answers2