Thread: how to generate random number between two numbers?

  1. #1
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    how to generate random number between two numbers?

    How can I generate a random number between two numbers using stdlib?

    printf("%d\n", rand() % 50); generates a number between 0 and 49, but how can I generate numbers between 10 and 20 or -10 and 10 with and without decimals? Is it possible with rand() ?

  2. #2
    C++ Witch laserlight's Avatar
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    Yes, it is possible, and you basically asked this in a previous post.

    Feel free to peruse the further discussion in that post, but as I noted if you care about the quality of your PRNG, you should use a specific PRNG, not rand(). If you are satisfied with rand() despite its loose requirements, then the (rand() % (n - m + 1) + m) approach to generate a random integer in the range [m, n] is fine.
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

  3. #3
    TEIAM - problem solved
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    Remember that a random number between 10 and 20 is the same as a random number between 0 and 10 plus 10. i.e. Get a random number between 0 and 10 and add 10 to it

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