在用户输入期间停止在空白行(C++)

#include<iostream>
#include<string>

int main() {
    std::string line;

    while (true) {
        std::cout << "Enter a line (type 'quit' to exit): ";
        std::getline(std::cin, line);

        if (line == "quit") {
            break;
        }

        if (line.length() == 0) {
            std::cout << "Blank line detected!"<< std::endl;
        } else {
            std::cout << "Non-blank line detected: "<< line<< std::endl;
        }
    }

    return 0;
}