..........

　　void func(int *p)

　　{...........}

　　..........

　　main()

　　{

　　int num=0;

　　.........

　　func(&num);

　　........

　　}

　　..........

　　here, the function argument “&num” is passed .

　　a. by value b. by reference

　　iii. practice

　　create a tree, which has h (h>0) layers, and its each node has w (w>0) sub-nodes.

　　please complete the following incomplete solution.

　　#include

　　#include

　　struct tree{

　　char info;

　　p_sub; //link to sub-nodes

　　};

　　// allocate memory and initiate

　　void dnode ( struct tree* tmp )

　　{

　　=malloc( sizeof (struct tree) );

　　= 0x41;

　　= null;

　　}

　　struct tree *dtree (struct tree* subtree, int height, int width)

　　{

　　int i;

　　if ( !subtree ) //if necessary, allocte memory for subtree

　　denode(subtree);