Gurobi linear expression object. A linear expression consists of a constant term, plus a list of coefficient-variable pairs that capture the linear terms. Linear expressions are used to build constraints. They are temporary objects that typically have short lifespans.
GRBLinExpr class is a sub-class of the abstract base
You generally build linear expressions by starting with an empty expression (using the GRBLinExpr constructor), and then adding terms. Terms can be added individually, using addTerm, or in groups, using addTerms, or multAdd. Terms can also be removed from an expression, using remove.
Note that a linear expression may contain multiple terms that involve the same variable. These duplicate terms are merged when creating a constraint from an expression, but they may be visible when inspecting individual terms in the expression (e.g., when using getVar).