Home / Questions / 35425
Accepted
Jogofus
Asked: 2020-11-23 18:24:56 +0800 CST 2020-11-23 18:24:56 +0800 CST

Doubt with cin.get()

  • 772

I am now with conditional statements and logical operators, and the following problem arises.

If I have the following code:

string deporte;
cout << "Indica tu deporte favorito: ";
cin.get();
getline(cin, deporte);

if (deporte == "futbol" || deporte = "baloncesto")
    cout << "Te gustan los deportes de equipo" << endl;
else
    cout << "Lo tuyo son los deportes individuales" << endl;

The fact is that this way it does execute correctly, but if on the contrary I delete cin.get(), the program goes directly to elsewithout giving the user the option to enter the data.

What am I doing wrong?

Thanks.

c++

1 Answers

  1. Best Answer

    The problem is not in the code you present but in the code that precedes it.

    A read operation does not have to remove the line break that the user enters:

    std::string var;
std::cout << "Escribe una palabra: ";
std::cin >> var; // no se elimina el salto de línea
std::cout << var << '\n';
std::cout << "Ahora escribe una frase: ";
std::getline(std::cin,var); // Se lee una cadena vacía

    The solution to this problem is by discarding whatever is in the input buffer before calling getline.

    If you assume that the user is going to use the program correctly and you know that the previous read operation is going to leave that character hanging there, you can choose to eliminate it with cin.get:

    std::string var;
std::cout << "Escribe una palabra: ";
std::cin >> var; // no se elimina el salto de línea
std::cout << var << '\n';
cin.get(); // Se descarta el salto de línea
std::cout << "Ahora escribe una frase: ";
std::getline(std::cin,var); // Se lee la frase esperada

    However, you can opt for a more generic solution that passes by eliminating the entire content of the input buffer and is using cin.ignore. This mechanism will allow the program to work even if the user turns into a monkey pounding the keyboard unceremoniously:

    string var;
std::cout << "Escribe una frase: ";
std::cin >> var; // no se elimina el salto de línea
std::cout << var << '\n';
std::cin.ignore(std::numeric_limits<std::streamsize>::max(),'\n'); // Se elimina el contenido del buffer de entrada
std::cout << "Escribe otra frase: ";
std::getline(std::cin,var); // Se lee la frase esperada
std::cout << var;
    • 2