The problem object instantiated by CPXcreateprob() represents an empty problem that contains no data; it has zero constraints, zero variables, and an empty constraint matrix. This empty problem object must be populated with data. This step can be carried out in several ways.

• The problem object can be populated by assembling arrays of data and then calling CPXcopylp() to copy the data into the problem object. (For example, see Building and Solving a Small LP Model in C on page 111.)
• Alternatively, you can populate the problem object by sequences of calls to the routines CPXnewcols(), CPXnewrows(), CPXaddcols(), CPXaddrows(), and CPXchgcoeflist(); these routines may be called in any order that is convenient. (For example, see Adding Rows to a Problem: Example lpex3.c on page 131.)
• If the data already exist in a file using MPS format or LP format, you can use CPXreadcopyprob() to read the file and copy the data into the problem object. (For example, see Reading a Problem from a File: Example lpex2.c on page 122.)