allocaton of memory

node *getnode()
    {
        node *x;
        x = (node*)malloc(sizeof(node));
        if (x==NULL)
            {
                    printf("no memory \n");
                    exit(1);
            }
        return x;
    }


*insert_rear(int item ,node *first)
    {
        node  *temp;
        node  *cur;
        temp = getnode();


      开发者_C百科  temp -> data = item;
        temp -> next = NULL;

        if (first == NULL)
        return temp;

        cur = first;
        while(cur -> next != NULL)
          {
            cur = cur -> next;
          }

        cur -> next = temp;
        return first;
    }

in insert_rear when the function calls getnode it goes to the above function, and it creates a node, while debugging using gdb when i did

(gdb) p temp
$7 = (struct classifier *) 0x8d8f080
(gdb) p &temp
$8 = (struct classifier **) 0xbff9cb04

what is the difference between the two.

In the

p &temp

you are printing the stack address for the variable temp. With

p temp

you are printing the value of temp (which is the address of the allocated memory returned by getnode()

You can have multiple indirections: temp has received a pointer address from getnode() that points to a node memory allocated by malloc.

&temp is the address of the memory that store this address (that points to the node).

Basically you have

&temp ---(points to)---> Memory X ***temp*** ---(points to)---> Memory Y ****MEMORY from malloc of "type" node**** 

So if you use *temp you are accessing the node. And if you are using *(&temp) (don't know if it's valid syntax...) but you would be accessing temp which stores the address where the node is stored.