What are the rules of the std::cin object in C++?

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情话喂你
情话喂你 2021-01-16 13:25

I am writing a small program for my personal use to practice learning C++ and for its functionality, an MLA citation generator (I\'m writing a large paper with tens of citat

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  •  清酒与你
    2021-01-16 14:02

    What is happening here is that std::cin >> firstName; only reads up to but not including the first whitespace character, which includes the newline (or '\n') when you press enter, so when it gets to getline(std::cin, articleTitle);, '\n' is still the next character in std::cin, and getline() returns immediately.

    // cin = "Bloggs\nJoe\nMan of Steel, Woman of Kleenex\n"
    std::cin >> lastName;
    std::cin >> firstName;
    // firstName = "Joe", lastName = "Bloggs", cin = "\nMan of Steel, Woman of Kleenex\n"
    getline(std::cin, articleTitle);
    // articleTitle = "", cin = "Man of Steel, Woman of Kleenex\n"
    

    Adding 'std::cin >> std::ws' (ws meaning whitespace) before your calls to getline() fixes the problem:

    std::cin >> firstName >> std::ws;
    getline(std::cin, articleTitle);
    

    But it is easier to see where you missed it if you do it in the argument:

    std::cin >> firstName;
    getline(std::cin >> std::ws, articleTitle);
    

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