Removing constraint from a model in gurobi c++ - c++

Question

I have one constraint set
after some modification I have to remove this constraint:model.addConstr(LHS10_2 <= LHS10_1)set from the model. model.remove() is not working. How can I do it?
Thank for your help.
model.remove(LHS10_2 <= LHS10_1) can not work.
for (i = 1; i <= ULD; i++)
{
for (j = 1; j <= station; j++)
{
GRBLinExpr LHS10_1 = 0;//自載飛航節線
GRBLinExpr LHS10_2 = 0;//他航載飛航節線
for (k = 2; k <= load; k++)
{
if (k == 2 || k == 3 || k == 7)
{
for (l = 1; l <= (node - 2); l++)
{
for (m = 1; m <= Num_FAn[j][k][l]; m++)
{
LHS10_1 += p*X[i][j][k][l][FSAn[j][k][l][m]][FLAn[j][k][l][m]][FNAn[j][k][l][m]];
}
}
}
if (k == 4 || k == 5)
{
for (l = 1; l <= (node - 2); l++)
{
for (m = 1; m <= Num_FAn[j][k][l]; m++)
{
LHS10_2 += X[i][j][k][l][FSAn[j][k][l][m]][FLAn[j][k][l][m]][FNAn[j][k][l][m]];
}
}
}
}
model.addConstr(LHS10_2 <= LHS10_1);
}
}

Answer 1

The method GRBModel::addConstr() returns an GRBConstr object that you should save in a local variable. Then at a later point in time, you can use the GRBModel::remove() method to delete that particular constraint from the model again, i.e., you could do something like
// Array to hold added constraint objects
GRBConstr* c = new GRBConstr[nConstr];
for (int k = 0; k < nConstr, ++k) {
// Create expressions LHS10_2 and LHS10_1 as needed
// [...]
// Add k-th constraint, grap object for later removal from model
c[k] = model.addConstr(LHS10_2 <= LHS10_1);
}
// Do some stuff, optimize, etc.
// [...]
// now delete unwanted constraints from model
for (int k = 0; k < nConstr, ++k) {
model.remove(c[k]);
}