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This is a discussion on New student within the C Programming forums, part of the General Programming Boards category; I wanted the help with the getchar() function....

  1. #1
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    New student

    I wanted the help with the getchar() function.

  2. #2
    Its hard... But im here swgh's Avatar
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    There is an FAQ on this on this site.
    I'm just trying to be a better person - My Name Is Earl

  3. #3
    Deathray Engineer MacGyver's Avatar
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    Code:
    int c;
    
    c = getchar();
    if(c != EOF)
    {
        /* Do something with char.... */
    }

  4. #4
    Frequently Quite Prolix dwks's Avatar
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    There is one thing to note when mixing getchar() with other input functions. scanf() often leaves extra characters in stdin: for example, if you typed "10\n" and scanf() was looking for a number, it would take the "10" but leave "\n" in the input stream. Then if you used getchar() immediately afterwards to get a character, you'd end up with the newline, which was probably not what you intended.

    If you use scanf() and then getchar(), you can eliminate any characters that scanf() may have left behind like so:
    Code:
    int c;
    
    while((c = getchar()) != '\n' && c != EOF);  /* flush the input stream */
    
    c = getchar();  /* the actual character */
    [edit]
    I wanted the help with the getchar() function.
    Do you still want help? [/edit]
    Last edited by dwks; 05-24-2007 at 03:04 PM.
    dwk

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  5. #5
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    What are you trying to do?

  6. #6
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    Quote Originally Posted by dwks View Post
    There is one thing to note when mixing getchar() with other input functions. scanf() often leaves extra characters in stdin: for example, if you typed "10\n" and scanf() was looking for a number, it would take the "10" but leave "\n" in the input stream. Then if you used getchar() immediately afterwards to get a character, you'd end up with the newline, which was probably not what you intended.

    If you use scanf() and then getchar(), you can eliminate any characters that scanf() may have left behind like so:
    Code:
    int c;
    
    while((c = getchar()) != '\n' && c != EOF);  /* flush the input stream */
    
    c = getchar();  /* the actual character */
    [edit]
    Do you still want help? [/edit]
    does that work when the input stream is empty?

  7. #7
    Deathray Engineer MacGyver's Avatar
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    No, it doesn't in the sense that it will block for input and accept new input just to throw it away.

    Only call it when you are aware that the input stream should contain at least one excess char.

  8. #8
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    but how to solve it when it is unknown wether the stdin buffer is empty or not empty?

    my solution is to set buffering to NULL before getchar(), but I don't think that is a nice solution

  9. #9
    Fear the Reaper...
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    You should really read the FAQ entry on this subject.

    Here. I'll do the work for you :
    http://faq.cprogramming.com/cgi-bin/...&id=1043284392
    and
    http://faq.cprogramming.com/cgi-bin/...&id=1043284385
    Teacher: "You connect with Internet Explorer, but what is your browser? You know, Yahoo, Webcrawler...?" It's great to see the educational system moving in the right direction

  10. #10
    Deathray Engineer MacGyver's Avatar
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    Quote Originally Posted by taisao View Post
    but how to solve it when it is unknown wether the stdin buffer is empty or not empty?
    It requires an OS/compiler specific method.

    Quote Originally Posted by taisao View Post
    my solution is to set buffering to NULL before getchar(), but I don't think that is a nice solution
    I don't believe that's a portable method. You are better off writing an OS/compiler specific method imo.

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