Generating random number from set

This is a discussion on Generating random number from set within the C Programming forums, part of the General Programming Boards category; The problem asks me to write a c statement that will assign an int variable a random number from [25, ...

  1. #1
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    Generating random number from set

    The problem asks me to write a c statement that will assign an int variable a random number from [25, 50, 75, 100]

    I am thinking of using rand() but I'm not sure how

    perhaps?
    for (int i = 0; i <=100;i*2)
    int random_number=rand(i);

    I'm not even sure that's allowed
    Last edited by Hybodus; 12-20-2010 at 09:51 AM.

  2. #2
    Gawking at stupidity
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    I would put your set in an array:
    Code:
     int set[] = { 25, 50, 75, 100 };
    Then you can use your rand() result as an index into set:
    Code:
     int random_number = set[<random number between 0 and 3 inclusive>];
    If you understand what you're doing, you're not learning anything.

  3. #3
    C++ Witch laserlight's Avatar
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    itsme86's suggestion is a more general solution, but in this case you can map the integers in the range [0, 3] to those numbers by a simple formula, e.g., ((rand() % 4 + 1) * 25).
    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

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