randomize

This is a discussion on randomize within the C++ Programming forums, part of the General Programming Boards category; \hey everyone.. i'm looking it up, and i can find ways to randomize a number from 0 to whatever, but ...

  1. #1
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    randomize

    \hey everyone.. i'm looking it up, and i can find ways to randomize a number from 0 to whatever, but how do you get a random number from lets say -500 to 500?

    any help would be appreciated, thanks

  2. #2
    Ethereal Raccoon Procyon's Avatar
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    Aug 2001
    Posts
    189
    Try this:

    Code:
    int R(int min, int max)
    {
       return (rand() % (max - min)) + min;
    }

  3. #3
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    Sep 2001
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    412
    That code you posted gives a rand from min to max-1.

    If you input, say, 0 as min, and 10 as max, it would be equal to rand()%10 + 0 -> which gives 0-9, not 1-10.

    To get a number between min and max inclusive, use this:

    Code:
    int R(int min, int max){
         return (rand() % (max + 1 - min)) + min;
    }

  4. #4
    Ethereal Raccoon Procyon's Avatar
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    189
    True. Whether you want inclusive or exclusive on either or both ends depends on the application, I suppose, but probably it's most logical to include that extra +1, as you probably wouldn't want R(0,1) to always return zero.

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