int QSget_colnames (QSprob p, char **colnames)

A QSprob data structure always contains names for each column of the LP problem; if the application does not give explicit column names, then the QSopt library will generate them when the problem is loaded and as new columns are added. The QSget_colnames function will allocate memory for each of the strings that are returned via the array of pointers in colnames; when the application no longer needs the names, the memory associated with each of the strings should be freed; since the memory for the strings was allocated by the QSopt library, the memory must be freed with calls to QSfree rather than by the system free() function.

/* p is an initialized QSprob, a handle to an existing LP problem  */

int rval, ncols, j;
char **colnames;

ncols = QSget_colcount (p);
colnames = (char **) malloc (ncols * sizeof (char *));

rval = QSget_colnames (p, colnames);
if (rval) {
    fprintf (stderr, 
             "Could not get column names, error code %d\n", rval);
} else {
    printf ("Variable Names\n");
    for (j = 0; j < ncols; j++) {
        printf ("%s\n", colnames[j]);
    }

    /* Need to free the individual names */

    for (j = 0; j < ncols; j++) {
        /* Use QSfree for mem allocated by QSopt */
        QSfree (colnames[j]);  
    }
}

/* Use free for mem allocated by system malloc */
free (colnames);