how do I change variable type with c++ API?

Answered

dapei jiang

• May 17, 2021 11:39
• Edited

Hi, everyone, I'm practice with the diet_c++.cpp, I want to change the variable type, I modified the API like below, but the results show it doesn't work, could anyone tell me what mistake I was take?

Thanks.

 

// Create decision variables for the nutrition information,
// which we limit via bounds
nutrition = model.addVars(minNutrition, maxNutrition, nullptr, 0, Categories, nCategories);
//nutrition->set(GRB_CharAttr_VType, GRB_INTEGER); //修改变量类型为整型变量
for (size_t p = 0; p < nCategories; ++p)
{
nutrition[p].set(GRB_CharAttr_VType, GRB_INTEGER);
}

// Create decision variables for the foods to buy
buy = model.addVars(nullptr, nullptr, cost, 0, Foods, nFoods);
//buy->set(GRB_CharAttr_VType, GRB_INTEGER);
for (size_t p = 0; p < nCategories; ++p)
{
buy[p].set(GRB_CharAttr_VType, GRB_INTEGER);
}

 

0

• 

  Jaromił Najman

  Gurobi Staff

  • May 17, 2021 12:14
  • Edited

  Hi Dapei,

  Except for

  for (size_t p = 0; p < nCategories; ++p)
  {
    buy[p].set(GRB_CharAttr_VType, GRB_INTEGER);
  }

  which should read

  for(size_t p = 0; p < nFoods /* there are only nFoods "buy" variables */; ++p)
  {
    buy[p].set(GRB_CharAttr_VType, GRB_INTEGER);
  }

  the code looks fine. Why do you think that it does not work?

  Best regards,
  Jaromił

  0
• 

  dapei jiang

  • May 17, 2021 12:24

  

  

  

  oooooooooh! I make a foolish mistake, I'm so stupid. 

  Mr Najman, Thank you!

  0

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