[Introduction to algorithms] changing the value referred to by the pointer as a formal parameter (Binary sorting tree)

Example 1: assign values to two null pointers.

# Include "stdio. H"

# Include "malloc. H" # Include "string. H" Void testfunction (char ** ptr1, char * & ptr2) // I often like to use * & ptr2 { * Ptr1 = "ABC "; Ptr2 = (char *) malloc (6 ); Strcpy (ptr2, "ABC "); }
Int main () { Char * ptr1 = NULL, * ptr2 = NULL; Testfunction (& ptr1, ptr2 ); Printf ("% s \ n", ptr1 ); Printf ("% s \ n", ptr2 ); Free (ptr2 ); }

Example 2: Implementation of binary sorting tree# Include "stdio. H"# Include "malloc. H"Struct Node{Int data;Node * right;Node * left;};Void insert (node * & root, node * & S) // The passed parameter is the key{If (root = NULL){Root = s;
}Else{If (root-> data <s-> data) // if the data to be inserted is greater than the node, insert the data to the rightInsert (root-> right, S );ElseInsert (root-> left, S );}}
Void creattree (node * & root, int A [], int N){Int I;Node * s;// Root = (node *) malloc (sizeof (node); // do not initialize or apply for space here. Root = NULL;For (I = 0; I <n; I ++){
S = (node *) malloc (sizeof (node ));S-> DATA = A [I];S-> right = NULL;S-> left = NULL;
Insert (root, S );}
}Void output (node * & root){If (root = NULL)Return;Else{Output (root-> left );Printf ("% 5d", root-> data );Output (root-> right );}}Int main (){Int A [] = {, 20 };Node * root;Root = (node *) malloc (sizeof (node); // (size of requested space)Root = NULL; // This sentence must not be less (initialized)Creattree (root, A, 11 );Output (Root );Return 0;}