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Mark Virtue question about while loop

This is a discussion on Mark Virtue question about while loop within the C Programming forums, part of the General Programming Boards category; I have put a comment in my code. Please answer this in as much detail as you can. This question ...

  1. #1
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    Mark Virtue question about while loop

    I have put a comment in my code. Please answer this in as much detail as you can. This question has been bugging me. I wish he said the answer in his video.

    Code:
    #include <stdio.h>
    
    
    main()
    {
          char        type;
          int         album; /* boolean */
          
          while (type != 'a' && type != 's')
          {
                printf("Album or single (a for album, s for single)? ");
                fflush(stdin);
                scanf("%c", &type);
                album = type == 'a';
                if (type != 'a' && type != 's') /* How come this has to be an and condition? Why wont the or condition work? */
                    printf("Error\n");
          }
          
          if (album)
             printf("Album\n");
          else
              printf("Single\n");
          
          fflush(stdin);
          getchar();
          
    }
    Thank you very much for any help you can give.

  2. #2
    Registered User whiteflags's Avatar
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    Because if it was one thing, it still isn't the other thing, and therefore entirely false. If you want it to be true when it was neither thing, that's completely different.

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    because you want to show an error only when the user gives an input that is not album and also not single.
    If you would put or there it will actually don't show an error never.
    Let's assume there is an or there. then the user inserted 's' (you don't want to give an error). it reaches the if statement and then asks "I am 'a'?" and the answer is not and then it gives an error.

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    Thank you for your answers, I can't believe I didn't realise that. I now see how it works.

    -Cheers.

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    Salem and inu11byte like this.

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    Quote Originally Posted by rags_to_riches View Post
    Can you please explain in more detail why I shouldn't use it? What's bad about it?

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    Quote Originally Posted by inu11byte View Post
    Can you please explain in more detail why I shouldn't use it? What's bad about it?
    See the red part of the message (#5)... well, that's a link... click on it and read...

    And FWIW... watching videos is NOT how you learn to program. Get a proper manual and go through it page by page compiling and working with all the examples as you go... People learn by doing, not by watching.

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    Quote Originally Posted by CommonTater View Post
    See the red part of the message (#5)... well, that's a link... click on it and read...

    And FWIW... watching videos is NOT how you learn to program. Get a proper manual and go through it page by page compiling and working with all the examples as you go... People learn by doing, not by watching.
    Sorry, I guess I was tired and didn't realise it was a hyper-link. I do the examples as I am watching. I can't learn by reading, only by seeing and doing.

  9. #9
    and the hat of wrongness Salem's Avatar
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    Not to mention the lousy S/N ratio - like 100MB of low quality video to get about 1K of useful information.
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    Quote Originally Posted by inu11byte View Post
    Sorry, I guess I was tired and didn't realise it was a hyper-link. I do the examples as I am watching. I can't learn by reading, only by seeing and doing.
    In all due respect, that is a tragic flaw in a programmer... How are you going to read the documentation for things like C Library functions and Windows API? The Standard C Library is a couple of hundred functions and the Windows API pushes 30,000 and I can pretty much guarantee there's no videos for any of it.

    Programmers spend a significant amount of their time "lookin' stuff up" to verify the syntax of function calls. In fact the documentation for the C Library is bigger than the library itself...

  11. #11
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    Quote Originally Posted by CommonTater View Post
    In all due respect, that is a tragic flaw in a programmer... How are you going to read the documentation for things like C Library functions and Windows API? The Standard C Library is a couple of hundred functions and the Windows API pushes 30,000 and I can pretty much guarantee there's no videos for any of it.

    Programmers spend a significant amount of their time "lookin' stuff up" to verify the syntax of function calls. In fact the documentation for the C Library is bigger than the library itself...
    I'm only watching videos for the starting part. Once I understand all the basics and the mastered a reasonable understanding of the language, I wont mind looking up functions. I learned Python and did the same with that.

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