scanf and printf precedence

This is a discussion on scanf and printf precedence within the C Programming forums, part of the General Programming Boards category; Hey, does anyone knows why scanf always comes before any printf? how do I print any thing before an input? ...

  1. #1
    Registered User
    Join Date
    Jun 2005
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    3

    Question scanf and printf precedence

    Hey,
    does anyone knows why scanf always comes before any printf? how do I print any thing before an input?

    PHP Code:
    int ab;
      
    printf("Enter 2 numbers:");
      
    scanf("%d %d", &a, &b);
      
    printf("%d %d"ab); 
    and it comes out:
    12 47
    Enter 2 numbers:12 47

  2. #2
    ATH0 quzah's Avatar
    Join Date
    Oct 2001
    Posts
    14,826
    Flush the output stream before calling scanf.
    Code:
    int a, b;
    printf("Enter 2 numbers:");
    fflush( stdout );
    scanf("%d %d", &a, &b);
    printf("%d %d", a, b);
    If you print with a newline at the end, it will flush the output. Without, it may or may not. It doesn't have to. So it's really dependant on your OS / compiler / whatever it feels like.
    Code:
    printf("foo\n"); /* flushes output... */
    printf("bar" ); /* doesn't */
    fflush is only designed for output streams. You can't flush input with it. Or rather, it's undefined behaviour if you try it.


    Quzah.
    Hope is the first step on the road to disappointment.

  3. #3
    Registered User
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    Jun 2005
    Posts
    3
    works like a charm. thank you

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