How to generate random numbers between 65 and 75

This is a discussion on How to generate random numbers between 65 and 75 within the C Programming forums, part of the General Programming Boards category; It makes it an unsigned number. Default is int, U makes it unsigned, L long 123U unsigned int 123UL unsigned ...

  1. #16
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    It makes it an unsigned number. Default is int, U makes it unsigned, L long

    123U unsigned int
    123UL unsigned long int
    123L long
    123LL long long

    I think there was a post about this somewhere edit: yeah see --v
    Last edited by robwhit; 03-02-2008 at 12:47 AM.

  2. #17
    Frequently Quite Prolix dwks's Avatar
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    Indeed -- well, I made one anyway.

    Literal UL
    dwk

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  3. #18
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    Quote Originally Posted by robwhit View Post
    It makes it an unsigned number. Default is int, U makes it unsigned, L long

    123U unsigned int
    123UL unsigned long int
    123L long
    123LL long long

    I think there was a post about this somewhere edit: yeah see --v
    OK, I thought it was something like that, but I've only seen 'f' used before for floating point numbers.
    Is the U actually required in that case, or would the compiler automatically assume you're talking about an unsigned number based on the context in which it's used?

  4. #19
    Frequently Quite Prolix dwks's Avatar
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    Integral promotion would promote, say, an int to an unsigned int. Basically, all operands of an expression are converted to the "largest" type, or widest, or whatever. signed char is the lowest, then unsigned char, then signed short, and so on, until unsigned long (or unsigned long long, if it exists); then float, then double.
    dwk

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  5. #20
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    Quote Originally Posted by cpjust View Post
    Although I'm sure the article is correct, I still have no idea why using (rand() % n) is wrong or what that whole thing about the low order bits was talking about? I also don't know why seeding it with time() wouldn't work very well (assuming you wait > 1 second between seeds)?
    Using rand() % n is not wrong. It has some issues you should be aware of.

    And the thing about lower order bits not being very random is outdated information, but still relevant on some old systems.

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