Thread: typedef structures

typedef Struct node {
char elem;
struct node * next;
} StackType;

typedef StackType * StackPtr;
StackPtr top;

is now StackPtr a type of variable?? and top is a variable of StackPtr type??

i get confused going from

struct node {
int val;
struct node *next;
};

to

typedef struct node{
char elem;
struct node *next;
}StackType;

these two structures are essentially the same thing, right???????


if that is the case, then is the following correct

Code:

correcting errors in this fragment:

void push (StackPtr *top, char p)
{
StackPtr newptr;
newptr = malloc();
newptr.elem = p;
newptr->next = top;
top = newptr;
}

should be changed to

Code:

void push(StackPtr *top, char p)
{
StackPtr newptr;
newptr=malloc(sizeof(StackPtr));
newptr->elem = p;
newptr->next = top;
top = newptr;
}

Quzah, your sizeof was of StackType, mine was sizeof StackPtr.
Does it make a difference??? Seems it would, now that I think about it, cuz StackType is a structure type and StackPtr is just a variable of that type. Right??

Instead of using the old, P-style declarations

Code:

//  ----p-style----

typedef Struct node { 
char elem; 
struct node * next; 
} StackType; 

typedef StackType * StackPtr; 
StackPtr top;

Let's do it this way instead-- much more readable--

Code:

typedef Struct node
   { 
   char elem; 
   struct node *next; 
   }StackType,*StackPtr;

StackPtr top;

enjoy.