c - Programmatic access to MathProg solutions in GLPK -

i have problem expressed in mathprog doesn't seem describable using c api. specifically, have constraints between variables. i've generated mathprog file , passed glpk. finds correct solution, don't see how access solution programmatically. returned glp_prob struct has no rows or columns. parse solution printed solver, i'm hoping there's better way.

alternatively, if it's possible express constraints between variables using c api, suspect solve problem. mathprog code below.

param t := 200; set b, dimen 3; set c, dimen 2; set s, dimen 2;  set q := setof{(i,j,c) in b : j == 1} i; set := setof{(i,s) in s} i; set e := setof{(i,j) in q cross i} (i, j);  var x{(i,j) in e}, >=0, <=1, binary; var y{i}, >=0, <=1, binary;  maximize obj :   sum{(i,j,c) in b} x[i,j] * c;  s.t. q1c:   sum{(i,s) in s} x[1,i] <= 1;  s.t. q2c:   sum{(i,s) in s} x[2,i] <= 1;  s.t. size :   sum{(i,c) in c} c * y[i] <= t;  s.t. c111avail :   x[1,1] <= y[1];  s.t. c122avail :   x[1,2] <= y[2];  s.t. c131avail :   x[1,3] <= y[1];  s.t. c132avail :   x[1,3] <= y[2];  s.t. c243avail :   x[2,4] <= y[3];  solve;  printf "set:"; printf {(i,s) in s: y[i] == 1} " %i", i; printf "\nnot set:"; printf {(i,s) in s: y[i] == 0} " %i", i; printf "\n";  data;  set c :=   1 100   2 100   3 100   4 100 ;  set s :=   1 100   2 100   3 200   4 100 ;  set b :=   1 1 30   1 2 30   1 3 75   1 4 0   2 1 0   2 2 0   2 3 0   2 4 35 ;  end; 

there additional glpk api routines can use after solving problem. like

glp_get_row_prim(lp, i) glp_get_col_prim(lp, i) 

which return primal value of row/column floating point number.

to generate matrix representation of inequalities between 2 variables (for example c api routines), have reformulate equations, variables on left hand side of equation. example

x[1, 1] <= y[1]; 

will turn into

y[1] - x[1, 1] >= 0;