Question

This is the def of my structure

    typedef struct treeNode
     {
        int data,pos;
        char name[16];
        struct treeNode *left;
        struct treeNode *right;
     }treeNode;

I have created an dynamic object

treeNode *temp;
            temp = (treeNode *)malloc(sizeof(treeNode));

If I have to assign a value to data how should I assign

scanf("%d",temp->data);   //or
scanf("%d",&(temp->data)); //why? because all scanf will look for is address to a location which could be done by temp->data;

and this goes for accessing data also i.e. how should I access the integer part ?

temp->data; //or
*(temp->data) 

Answer 1

scanf("%d",&temp->data);

Because scanf() needs address of variable. For each conversion specifier, scanf() expects the corresponding argument to be a pointer to the proper type: %d expects an argument of type int *, %f expects an argument of type double *, %c and %s both expect an argument of type char *, etc.

Behaviour of scanf() gives more idea about scanf().

for accessing temp->data is enough, because it is essentially equivalent to (*temp).data.

If you try to access *(temp->data) then you trigger undefined behaviour. Because, you are accessing a memory location which may be in other process’s context.

say temp->data is 100, then *(temp->data) means *(100), i.e accessing at memory location 100.