Initialization of variables matrix in a structure C

Question

I have this struct:

typedef struct { int mat[x][x]; int res; } graphe;
graphe g;

the problem that I can't access to the graph matrix

for example when I set :

int m[5][5]={{0,1,1,1,0},{1,0,1,1,0},{1,1,0,1,1},{1,1,1,0,1},{0,0,1,1,0}};
graphe g = { m[5][5], 5};

for(i=0;i<lignes;i++)
    {
        for(j=0;j<lignes;j++)
        {
            printf("%i ",g.mat[i][j]);
        }
        printf("\n");
    }
printf("Res = %i ",g.res);

I have

0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
Res =0

Normally should be:

0 1 1 1 0
1 0 1 1 0
1 1 0 1 1
1 1 1 0 1
0 0 1 1 0
Res =5

Can you help me?

Answer 1

graphe.mat is 25 (probably, it has to be at least 25 in this case) bytes of reserved memory inside the struct. But m is a pointer to another memory location. Neither C nor C++ allow to assign m to the struct's member.

If you have to copy data into the struct you have to use memcpy and friends. In case of copying the strings you need to handle the '\\0' terminator too.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct { int mat[5][5]; int res; } graphe;

int main(void) {
int m[5][5]={{0,1,1,1,0},{1,0,1,1,0},{1,1,0,1,1},{1,1,1,0,1},{0,0,1,1,0}};
graphe g;
memcpy( g.mat, m, sizeof(m));

example

Answer 2

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct { int mat[5][5]; int res; } graphe;

int main(void) {
int m[5][5]={{0,1,1,1,0},{1,0,1,1,0},{1,1,0,1,1},{1,1,1,0,1},{0,0,1,1,0}};
graphe g;
memcpy( g.mat, m, sizeof(m));
g.res= 5;
for(i=0;i<lignes;i++)
    {
        for(j=0;j<lignes;j++)
        {
            printf("%i ",g.mat[i][j]);
        }
        printf("\n");
    }
printf("Res = %i ",g.res);

be careful when using array 2D is not a simple affectation like simple variable (like g.res), because you have to indicate the size of your array, so you have to use memcpy for that.