Dev C++ |Random Coding| Not Working!

This is a discussion on Dev C++ |Random Coding| Not Working! within the C++ Programming forums, part of the General Programming Boards category; i am now trying to make random values. here is my simple lil program to learn more about it. it ...

  1. #1
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    Dev C++ |Random Coding| Not Working!

    i am now trying to make random values. here is my simple lil program to learn more about it. it has a error when i compile tho.

    Code:
    #include <iostream>
    #include <cstdlib>
    
    const int LOW = 1;
    const int HIGH = 6;
    
    int main()
    {
    int firstdie;
    int secdie;
    
    firstdie = rand() % (HIGH - LOW);
    secdie = rand() % (HIGH - LOW);
    
    cout << "You rolled a " << firstdie;
    cout << "\n\nAnd you rolled a " << secdie;
    system("pause");
    }
    the compiling errors are:

    C:\My Documents\C++ Stuff\Un-Important Working Programs\random.cpp
    [Warning] In function `int main()':

    15 C:\My Documents\C++ Stuff\Un-Important Working Programs\random.cpp
    `cout' undeclared (first use this function)

    15 C:\My Documents\C++ Stuff\Un-Important Working Programs\random.cpp
    (Each undeclared identifier is reported only once for each function it appears


    thx alot!

  2. #2
    The Defective GRAPE Lurker's Avatar
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    Add after includes:
    Code:
    using namespace std;
    or even better:
    Code:
    using std::cout;
    using std::rand;
    Do not make direct eye contact with me.

  3. #3
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    cant beleive i forgot that! thx so much man! check ur game thread too, i replied in it. but now, each time it is run, i roll a 1 and a 2 each time. im wondering if its that seeding the random value thing i have to do(which i dont understand and need help with), or just what i rolled. u know? thx

  4. #4
    Registered User manofsteel972's Avatar
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    Have to use srand() to seed the timer

    use the following at the beginning of the program and only execute it once to seed the random number genrator with the system time

    Code:
    srand ( (unsigned)time(NULL) );
    "Knowledge is proud that she knows so much; Wisdom is humble that she knows no more."
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    Operating Systems=Slackware Linux 9.1,Windows 98/Xp
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    Now I know what doesn't work.

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  5. #5
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    execute it once? like compile the prog with that code in it(before int main() right?), then delte the code after? what do u exactly mean by execute the program only once? i might distribute the program or sumthin!

  6. #6
    Rabite SirCrono6's Avatar
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    He means, do NOT place srand in a loop or a recursive function. This is because if you have your seed set to
    the clock and put in a loop, as you
    know a loop takes much less than a second, so it will end up turning up the same thing till a second has
    passed (assuming this is how you seed rand):

    Code:
    #include <iostream>
    #include <cstdlib>
    #include <ctime>
    
    int main( void )
    {
      int Number;
      srand( time( 0 ) ); //As I do it...
      Number = rand % ( 12 - 6 + 1 ) + 6; //This will generate a number between 12 and 6, substitue 12   
      std::cout << "You random number is: " << Number; //for your high number and 6 for your low...
      return 0;
    }
    An example of a bad way to use srand:

    Code:
    #include <iostream>
    #include <cstdlib>
    #include <ctime>
    
    int main( void )
    {
      int Number;
      for( int C = 0; C < 10; C++ )
      {
        srand( time( 0 ) );
        Number = rand % ( HIGH - LOW + 1 ) + LOW;
        std::cout << Number << ' ';
      }
      return 0;
    }
    Since the seed is placed in the loop and it is using seconds to seed rand, the loop will happen several times
    a second, producing the same number several times. Say HIGH is 5, and LOW is 1:

    1111444422...

    That is an example, it will use the same number several times before switching to another number.

    - SirCrono6
    Last edited by SirCrono6; 03-05-2004 at 10:05 PM.
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  7. #7
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    wow, thx for the examale. lemme go try it, brb.

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