In this particular example, the planning period is six months, and there are five kinds of oil to be blended. Those details are represented as constants, like this:

const IloInt nbMonths   = 6;
const IloInt nbProducts = 5;

The five kinds of oil (vegetable and non vegetable) are represented by an enumeration, like this:

typedef enum { v1, v2, o1, o2, o3 } Product;

The varying price of the five kinds of oil over the six-month planning period is represented in a numeric matrix, like this:

      NumMatrix cost(env, nbMonths);
      cost[0]=IloNumArray(env, nbProducts, 110.0, 120.0, 130.0, 110.0, 115.0);
      cost[1]=IloNumArray(env, nbProducts, 130.0, 130.0, 110.0,  90.0, 115.0);
      cost[2]=IloNumArray(env, nbProducts, 110.0, 140.0, 130.0, 100.0,  95.0);
      cost[3]=IloNumArray(env, nbProducts, 120.0, 110.0, 120.0, 120.0, 125.0);
      cost[4]=IloNumArray(env, nbProducts, 100.0, 120.0, 150.0, 110.0, 105.0);
      cost[5]=IloNumArray(env, nbProducts,  90.0, 100.0, 140.0,  80.0, 135.0);

That matrix could equally well be filled by data read from a file in a large-scale application.