something that isnt supposed to happen but does anyway

This is a discussion on something that isnt supposed to happen but does anyway within the C++ Programming forums, part of the General Programming Boards category; i have never run into this problem before, but suddenly ive had two programs in a row that have started ...

  1. #1
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    something that isnt supposed to happen but does anyway

    i have never run into this problem before, but suddenly ive had two programs in a row that have started doing this, and i cant figure out why.

    a snippet of my code goes as follows:

    //...
    printf("Chose [blah blah] \n");
    scanf("%d\n", &choice);
    //[execute choice]

    and every time the program runs it makes you input twice... this is the output i get:

    Chose [blah blah]
    [user inputs number and hits enter]
    [number displays, but nothing else happens so user inputs number again]
    [choice executes]

    why is it making me put in the input twice? i have written two seperate programs lately that have this problem, and ive written numerous programs before in which i have never had a problem with it.

  2. #2
    Code Goddess Prelude's Avatar
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    It does that because scanf is retarded. If possible avoid using it for many reasons. cin also has a similar problem in that when the user enters input and hits enter, the newline remains in the input stream. The next call to cin or scanf or any character input function will result in the newline being read. The problem can be solved by either using
    cin.ignore();
    or
    while ( getchar() != '\n' );

    Both of which will clear the input stream by reading and discarding everything up to and including a newline. How do you avoid the problem altogether? Use fgets and cin.getline() to read everything into a string and parse that string into the data you need

    -Prelude
    My best code is written with the delete key.

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    hmm......


    being here just makes me feel retarded.

  4. #4
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    You might try scanf() without the newline(\n).

    Instead of:
    scanf("%d\n", &choice);

    Try:
    scanf("%d", &choice);

  5. #5
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    yeah, it works now.... thanks guys

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