# C# Attribute Examples

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### C# Attribute Examples

Consider the case where you have a Gurobi model m. You can retrieve the number of variables in the model by querying the NumVars model attribute (which is implemented as a .NET property):

  cols = m.NumVars;


If you've performed optimization on the model, the optimal objective value can be obtained by querying the ObjVal model attribute:

  obj = m.ObjVal;


If you'd like to query the value that a variable takes in the computed solution, you can query the X attribute for the corresponding variable object:

  vars = m.GetVars()
for (int j = 0; j < cols; j++)
xj = vars[j].X

You can also query the value of X for multiple variables in a single call using the Get method on the model m:
  double[] xvals = m.Get(GRB.DoubleAttr.X, m.GetVars()))


For each attribute query method, there's an analogous Set routine. To set the upper bound of a variable, for example:

  v = m.GetVars()[0]
v.UB = 0

(In this example, we've set the upper bound for the first variable in the model to 0).