Hierarchical structures

[momotaro]

those are my structers:
[CODE=c]
typedef struct _stud student;
typedef struct _grades grades;
struct _stud
{
char name[MAXSIZE];
grades gr;
};

struct _grades
{
double final;
char gpa;
};
[/CODE]

and this is the line where the code crach:

[CODE=c]
scanf("%lf", &s->gr.final);
[/CODE]
And those are the errors:
error C2079: 'gr' uses undefined struct '_grades'
error C2224: left of '.final' must have struct/union type

[JosAH]

Move lines 9-13 before line 3 because that _grades struct isn' defined yet when
the _stud struct is defined.

kind regards,

Jos

[momotaro]

but i thougt line 1 & 2 normaly solve this kind of problems???

[JosAH]

but i thougt line 1 & 2 normaly solve this kind of problems???

No they don't; typedefs just introduce a new name for another type; if the type
is an imcomplete type (in your case) just a new name for an incomplete type
is introduced by those typedefs.

kind regards,

Jos

[momotaro]

first question: could we do that kind of stuff?
[CODE=c]
typedef struct _stud student;
typedef struct _grades grades;
struct _stud
{
char name[MAXSIZE];
grades *gr; // **********a pointer a another struct*********
};

struct _grades
{
double final;
char gpa;
};
[/CODE]

second question: and how to acces it
is this correct:

[CODE=c]
//suppose that we have student s;
scanf("%lf", &s->gr->final);
[/CODE]

third question:
maybe we should allocate memory for *gr then..

plz help

[ilikepython]

first question: could we do that kind of stuff?
[CODE=c]
typedef struct _stud student;
typedef struct _grades grades;
struct _stud
{
char name[MAXSIZE];
grades *gr; // **********a pointer a another struct*********
};

struct _grades
{
double final;
char gpa;
};
[/CODE]

second question: and how to acces it
is this correct:

[CODE=c]
//suppose that we have student s;
scanf("%lf", &s->gr->final);
[/CODE]

third question:
maybe we should allocate memory for *gr then..

plz help

1)
Yes you can.
2)
If s is a pointer then that should work.
3)
You have to otherwise you will get a segmentation fault.
[code=c]
s->gr = (grades *)malloc(sizeof (grades));
[/code]