Query a single value from a character-valued array attribute.
A non-zero return value indicates that a problem occurred while querying the attribute. Refer to the Error Code table for a list of possible return values. Details on the error can be obtained by calling GRBgeterrormsg.
model: A loaded optimization model, typically created by routine GRBnewmodel or GRBreadmodel.
attrname: The name of a character-valued array attribute. Available attributes are listed and described in the Attributes section of this document.
element: The index of the requested array element.
values: A pointer to the location where the requested value should be returned.
char first_one; error = GRBgetcharattrelement(model, "VType", 0, &first_one);