randgen.h

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#ifndef _RANDGEN_H
#define _RANDGEN_H

#include <limits.h>                     // for INT_MAX

// designed for implementation-independent randomization
// if all system-dependent calls included in this class, then
// other classes can make use of this class in independent manner
// all random numbers are uniformly distributed in given range
//
// RandGen() ---      constructor sets seed of random # generator
//                    once per program, not per class/object
//     
// RandInt(int max)
// RandInt(int low,int max) - return random integer in range [0..max)
//                     when one parameter used, [low..max] when
//                     two parameters used
//
//       examples:    rnd.RandInt(6) is random integer [0..5] or [0..6)
//                    rnd.RandInt(3,10) is random integer [3..10]
//                    rnd.RandInt()  is random integer [0..INT_MAX)
//
// RandReal()       -- returns random double in range [0..1)
// RandReal(double low, double max) -- random double in range [low..max)

class RandGen
{
  public:
    RandGen();                          // set seed for all instances
    int RandInt(int max = INT_MAX);     // returns int in [0..max)
    int RandInt(int low, int max);      // returns int in [low..max]
    double RandReal();                  // returns double in [0..1)
    double RandReal(double low, double max); // range [low..max]

    static void SetSeed(int seed);      // static (per class) seed set
private:
    static int ourInitialized;          // for 'per-class' initialization
};

#endif