循环双向链表循环、插入、删除

#include "stdio.h"
#include "stdlib.h"

typedef int zlp;

typedef struct Node{
	zlp data;
	struct Node *pre,*next;
}Linklist;

Linklist *creat(){
	Linklist *head = (Linklist*)malloc(sizeof(Linklist));
	head->data=0;
	head->next=head;
	head->pre=head;
	
	return head;
}

void judement(Linklist *a){
	if((a=a->next)&&(a=a->pre)){
		printf("Linklinst creat successful!\n");
	}else{
		printf("Linklist creat fail!");
	}
}

Linklist *insert(Linklist *a,int pos,int num){
	Linklist *curr = a;
	while(pos>=1){
		curr=curr->next;
		--pos;
	}
	Linklist *temp = (Linklist*)malloc(sizeof(Linklist));
	temp->data=num;
	temp->next=curr->next;
	curr->next->pre=temp;
	curr->next=temp;
	temp->pre=curr;
	
	return a;
}

Linklist *dele(Linklist *a,int pos){
	Linklist *curr = a;
	while(pos>=1){
		curr=curr->next;
		--pos;
	} 
	Linklist *q = (Linklist*)malloc(sizeof(Linklist));
	q=curr->next;
	curr->next=q->next;
	q->next->pre=curr;
	free(q);
	return a;
	
}

void display(Linklist* a){
	Linklist *b = a->next;
	while(b!=a){
		printf("%d ",b->data);
		b=b->next;
	}
	printf("\n");
}

int main(){
	Linklist *a = creat();
	judement(a);
	insert(a,0,1);
	insert(a,1,2);
	insert(a,2,3);
	insert(a,3,4);
	insert(a,4,5);
	insert(a,5,6);
	display(a);
	dele(a,2);
	display(a);
	
	return 0;
}