R: [gecode-users] Simple example (x<2)

[Giuseppe Di Guglielmo]

> Please find attached a basic example that does what you want. 
> However, I would like to mention that Gecode is not really a 
> system meant for learning constraint programming as all of 
> its documentation already assumes a thorough knowledge of 
> connstraint programming.

Ok, I'm using ECLiPSe C++ API, but due some its bugs I need to change CLP
enviroment. 

Other question:
can I procede in this way with Gecode:

1. declaring some variable
2. post one or more constraints
3. retrieve the results
 
as in the following ECLiPSe example?
Can you post a Gecode equivalent slice of code? 

#include <iostream>
#include <eclipseclass.h>
//[...]

int main(int argc, char* argv[]) {
//[...] 
  // configuring some ECLiPSe variables
  char* ECLIPSE_HOME = getenv("ECLIPSE_HOME");

  ec_set_option_ptr(EC_OPTION_ECLIPSEDIR, (void *)ECLIPSE_HOME);
  ec_set_option_int(EC_OPTION_LOCALSIZE, 128*1024*1024);
  ec_set_option_int(EC_OPTION_GLOBALSIZE, 128*1024*1024);
  ec_init();
  EC_atom fail = EC_atom("fail");
  EC_atom random = EC_atom("random");
  post_goal("lib(ic)");
  EC_ref Search;
  
  // [1.]
////////////////////////////////////////////////////////////////////////
  // declare a variable (ECLiPSe type)
  EC_ref X_e;
  long X;
  // setting variable range
  post_goal(set_bounds(X_e, 0, 100));
  post_goal(term(EC_functor("indomain",2), X_e, random));
 
////////////////////////////////////////////////////////////////////////////
////

  // [2.]
////////////////////////////////////////////////////////////////////////
  // posting constraints
  // x < 50        
  post_goal(less_e(X_e,50));
  // x >= 30
  post_goal(geq_e(X_e,30));
 
////////////////////////////////////////////////////////////////////////////
///
           
  // [3.]
////////////////////////////////////////////////////////////////////////    
  // retrieve the results                          
  while (EC_succeed == EC_resume(Search)) {                
    if ((EC_word(X_e).is_long(&X) == EC_succeed)) {
      cout << "X : " << X << endl;
    } else {
      cout << "ERROR" << endl;
      return 1;
    }
    Search.cut_to();
    post_goal(fail);

  }

  ec_cleanup();
        
  return 0;
}

[...]