still cannot generate a random number between 0 and 1

This is a discussion on still cannot generate a random number between 0 and 1 within the C Programming forums, part of the General Programming Boards category; It was recommended that I try this: Code: double price = 30000 *rand() % 1; But that keeps giving me ...

  1. #1
    Registered User
    Join Date
    May 2012
    Location
    Milwaukee
    Posts
    26

    still cannot generate a random number between 0 and 1

    It was recommended that I try this:
    Code:
    double price = 30000 *rand() % 1;
    But that keeps giving me zero every time? Am I missing something?

    Thanks

  2. #2
    C++ Witch laserlight's Avatar
    Join Date
    Oct 2003
    Location
    Singapore
    Posts
    21,310
    Yes, the recommendation is wrong. You could read Prelude's article on using rand() as a starting point.
    C + C++ Compiler: MinGW port of GCC
    Version Control System: Bazaar

    Look up a C++ Reference and learn How To Ask Questions The Smart Way

  3. #3
    Registered User
    Join Date
    Mar 2011
    Posts
    546
    what does n % 1 produce?

    try a simple program that prints the results

    2 % 1
    3 % 1
    4 % 1
    5 % 1

    etc

  4. #4
    Registered User
    Join Date
    Dec 2011
    Posts
    795
    Are you trying to generate a random number that's EITHER 0 or 1, or are you trying to generate some sort of floating point value between 0 and 1?

    If the latter, then % and rand() are both integer-only operations and you need to find another way to do this. For example, if you wanted 2 places of precision:
    Code:
    float num = (float)((uint32_t)rand() % 100) / 100;

Popular pages Recent additions subscribe to a feed

Similar Threads

  1. how to generate a random number in c?
    By blogchama in forum C Programming
    Replies: 2
    Last Post: 01-20-2011, 09:39 AM
  2. Generate Random Number
    By peacealida in forum C++ Programming
    Replies: 10
    Last Post: 04-06-2008, 08:57 AM
  3. generate a random number
    By waxydock in forum C++ Programming
    Replies: 5
    Last Post: 06-05-2005, 07:43 PM
  4. Replies: 11
    Last Post: 07-16-2002, 11:39 AM
  5. Ask about generate Random number
    By ooosawaddee3 in forum C Programming
    Replies: 2
    Last Post: 07-01-2002, 04:30 AM

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21