All definitions needed for a ILOG CPLEX Callable Library program are imported by including file <ilcplex/cplex.h> at the beginning of the program. After a number of lines that establish the calling sequences for the routines that are to be used, the program's main function begins by checking for correct command line arguments, printing a usage reminder and exiting in case of errors.

Next, the data defining the problem are read from a file specified in the command line at run time. The details of this are handled in the routine readdata. In this file, cost, lower bound, and upper bound are specified for each type of food; then minimum and maximum levels of several nutrients needed in the diet are specified; finally, a table giving levels of each nutrient found in each unit of food is given. The result of a successful call to this routine is two variables nfoods and nnutr containing the number of foods and nutrients in the data file, arrays cost, lb, ub containing the information on the foods, arrays nutrmin, nutrmax containing nutritional requirements for the proposed diet, and array nutrper containing the nutritional value of the foods.