CPLEX generally does not need to be involved while you create your model. However, once the model is set up, it is time to create your cplex object, that is, an instance of the class IloCplex, to be used to solve the model. IloCplex is a class derived from IloAlgorithm.. There are other Concert Technology algorithm classes, also derived from IloAlgorithm.. Some models might also be solved by using other algorithms, such as the class IloSolver for constraint programming, or by using a hybrid algorithm consisting of both IloSolver and CPLEX. Some models, on the other hand, cannot be solved with CPLEX.

The makeup of the model determines whether or not CPLEX can be used to solve it. More precisely, in order to be handled by IloCplex objects, a model may only consist of modeling objects of the following classes:

For a description of special ordered sets see Using Special Ordered Sets (SOS). The last class, IloAnd, is listed for completeness only and is generally not used with CPLEX, except with the class IloSolution, as described in the ILOG Concert Technology User's Manual.