编程实现单链表的插入

Node *insert(Node **head,int index,int value){Node *p=*head;//头结点之前插入if (index<=0){Node* node=new Node();node->data=value;node->next=p;*head=node;}else{int i=0;Node *pre=p;while (p!=NULL&&i<index){pre=p;p=p->next;++i;}//在中间或者在尾部结点if (pre!=NULL&&i<=index){Node* node=new Node();node->data=value;node->next=p;pre->next=node;}}return *head;}