igraph attribute error

#include <igraph.h>


void f(igraph_t g, double number){

     igraph_real_t N = number;
     SETGAN(&g, "number", N);

}

int main(void){

    igraph_t g;
    float N = 50.0;
    igraph_integer_t Kin = 8.0;
    igraph_bool_t directed = 1;
    igraph_erdos_renyi_game(&g, IGRAPH_ERDOS_RENYI_GNM, N, N*Kin/2.0, directed, 0);
    int l = (int) N;

    igraph_i_set_attribute_table(&igraph_cattribute_table);

    f(g, 0.2);

return 0;
}