struct of structs as argument

Question

I have quite a big structure which has inside of it other structures, then I want to pass this structure of structures as an argument of a function. Anyone knows how to do it or may give me an example please!

Answer 1

struct B {
   //your struct..
};
struct A {  
    B b;
};

void foo(struct A a)
{ 
   a.b + ???....
   //you function
}

Answer 2

If your function doesn't need to modify any of the struct's contents, you can pass it like you would any other argument:

struct bigStruct {
  struct aStruct a;
  struct anotherStruct b;
  struct someOtherStruct c;
  ...
};

void foo( struct bigStruct s )
{
  do_something_with( s.a );
  do_something_else_with( s.b );
  ...
}

If you need to write to any of the struct's members, you will need to pass a pointer to the struct, and use the -> operator to access its members:

void bar( struct bigStruct *p )
{
   do_something_with( p->a );
   do_something_else_with( p->b );
   ....
}

Sometimes it's also desirable to use a pointer if the struct type is very large.

Note that you only need to use the -> operator when dealing with a pointer to a struct. In our struct definition above, a , b , and c are regular struct types, so we'd access their members with . . For example, assuming the following definition for aStruct :

struct aStruct {
  int ival;
  double dval;
  char name[20];
};

we'd access those members through p like so:

printf( "%d\n", p->a.ival );
printf( "%f\n", p->a.dval );
printf( "%s\n", p->a.name );

Now, if our bigStruct was defined like

struct bigStruct {
  struct aStruct *a;
  ...
};

then we'd need to use the -> operator for both the children of p and the children of p->a :

printf( "%d\n", p->a->ival );
printf( "%f\n", p->a->dval );
printf( "%s\n", p->a->name );

Answer 3

A structure may have both basic types and complex types as members. Passing a structure that has members that are in turn structures does not differ from passing a structure that only has basic type members.