双向链表插入删除

#include <stdio.h>

#include <stdlib.h>

typedef struct node_t {

int data;

struct node_t* prev;

struct node_t* next;

} node;

node* init( void )

{

node* p;

p = (node *)malloc(sizeof(node));

if( p == NULL ) {

printf("malloc error\n");

return 0;

}

p->prev = NULL;

p->next = NULL;

p->data = 0;

return p;

}

/* insert a new node after specified postion, postion 0 is available */

int insert_node( node* head, int pos, int data )

{

node* p;

node* q;

if ( head == NULL || pos < 0 ) {

printf("parameter error\n");

return -1;

}

q = head;

while ( pos-- > 0 && q != NULL ) {

q = q->next;

}

if ( q == NULL ) {

printf("parameter error\n");

return -1;

}

p = (node *)malloc(sizeof(node));

if( p == NULL ) {

printf("malloc error\n");

return -1;

}

p->prev = q;

p->next = q->next;

p->data = data;

/* Is the last node ? */

if ( q->next )

q->next->prev = p;

q->next = p;

return 0;

}

/* insert a new node after specified postion */

int remove_node( node* head, int pos )

{

node* q;

if ( head == NULL || pos <= 0 ) {

printf("parameter error\n");

return -1;

}

q = head;

while ( pos-- > 0 && q != NULL ) {

q = q->next;

}

if ( q == NULL ) {

printf("parameter error\n");

return -1;

}

q->prev->next = q->next;

/* Is the last node ? */

if ( q->next )

q->next->prev = q->prev;

free( q );

return 0;

}

void print_node( node* head )

{

node* p;

p = head->next;

while ( p ) {

printf("%d ", p->data);

p = p->next;

}

printf("\n");

}

int main( void )

{

node* head;

int n = 5;

head = init();

while ( n > 0 ) {

insert_node( head, 0, n );

n--;

}

print_node( head );

insert_node( head, 10, 10);

insert_node( head, 0, 0);

print_node( head );

insert_node( head, 6, 6);

print_node( head );

remove_node( head, 0 );

remove_node( head, 10 );

remove_node( head, 6 );

print_node( head );

remove_node( head, 6 );

print_node( head );

return 0;

}