string messageVar;
cout << "Type your message: ";
getline(cin, messageVar);

string messageVar;
cout << "Type your message: ";
cin.ignore();
getline(cin, messageVar);

std::cin.ignore();

std::cin.ignore(std::numeric_limits<std::streamsize>::max(), 'n');

int main(){
.... example with file
     //input is a file
    if(input.is_open()){
        cin.ignore(1,'n'); //it ignores everything after new line
        cin.getline(buffer,255); // save it in buffer
        input<<buffer; //save it in input(it's a file)
        input.close();
    }
}

main ()
{
    std::string name;

    std::cout << "Please, enter your full name: ";
    std::getline (std::cin,name);
    std::cout << "Hello, " << name << "!n";

    return 0;
}

getchar();