Compilare: user.c: In function ‘main’: user.c:19:13: warning: array subscript has type ‘char’ [-Wchar-subscripts] fscanf( fin, "%d", &mat[i][j] ); ^ user.c:19:13: warning: array subscript has type ‘char’ [-Wchar-subscripts] user.c:28:17: warning: array subscript has type ‘char’ [-Wchar-subscripts] c += mat[i][j] * (1 - 2 * ( ( bin >> i ) & 1 ) ); ^ user.c:28:17: warning: array subscript has type ‘char’ [-Wchar-subscripts] user.c:15:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%hhu%hhu", &n, &m ); ^ user.c:19:19: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf( fin, "%d", &mat[i][j] ); ^