# get_Ncolumns Returns the number of columns (variables) in the lp. int get_Ncolumns(lprec *lp); Return Value get_Ncolumns returns the number of columns (variables) in the lp. Parameters lp Pointer to previously created lp model. See return value of make_lp, copy_lp, read_lp, read_LP, read_mps, read_freemps, read_MPS, read_freeMPS, read_XLI Remarks The get_Ncolumns function returns the number of columns (variables) in the lp. Note that the number of columns can change when a presolve is done or when negative variables are split in a positive and a negative part. Therefore it is advisable to use this function to determine how many columns there are in the lp instead of relying on an own count. Example
    #include <stdio.h>
    #include <stdlib.h>
    #include "lp_lib.h"

    int main(void)
    {
      lprec *lp;
      int Ncolumns;

      /* Create a new LP model */
      lp = make_lp(0, 1);
      if(lp == NULL) {
        fprintf(stderr, "Unable to create new LP model\n");
        return(1);
      }

      Ncolumns = get_Ncolumns(lp); /* Will return 1 */

      set_presolve(lp, PRESOLVE_COLS);
      solve(lp);

      Ncolumns = get_Ncolumns(lp); /* Will return 0 */

      delete_lp(lp);
      return(0);
    }
lp_solve API reference See Also make_lp, copy_lp, read_lp, read_LP, read_mps, read_freemps, read_MPS, read_freeMPS, read_XLI, get_Norig_columns, get_Nrows, get_Norig_rows, get_orig_index, get_lp_index, get_Lrows