Thread: How does getchar work in this example?

  1. #1
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    Mar 2020
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    Post How does getchar work in this example?

    Hi!

    I'm working through K&R slowly and have encountered this example demonstrating getchar and putchar:

    Code:
    main()
    {
        int c;
    
        c = getchar();
        while (c != EOF) {
            putchar(c);
            c = getchar();
        }
    }
    I am confused how, each time getchar is called in the loop, it "remembers" which character it's up to in the text stream; how does it not just go straight back to the beginning of the text stream? If somebody could clarify how this works in this case, it would be greatly appreciated.

    Thanks!
    Last edited by c_beginner_; 03-27-2020 at 11:51 AM.

  2. #2
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    Think as the input text stream as a deck of cards.
    getchar removes the top card and returns its value.
    If there is no top card it returns EOF

    Tim S.
    "...a computer is a stupid machine with the ability to do incredibly smart things, while computer programmers are smart people with the ability to do incredibly stupid things. They are,in short, a perfect match.." Bill Bryson

  3. #3
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    Quote Originally Posted by stahta01 View Post
    Think as the input text stream as a deck of cards.
    getchar removes the top card and returns its value.
    If there is no top card it returns EOF

    Tim S.
    Thank you for the explanation, this makes it easier to understand now.

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