单链表的插入

typedef struct node
{
        int data;
        struct node *next;
}Node;

/*链表的插入(在指定位置之前插入)*/
void before_insert(Node *head, int position, int value)
{
        Node *p = head;
        Node *q = NULL;
        int i = 0;
        while(p && i++ < position - 1)
        {
                p = p->next;
        }
        q = (Node *)malloc(sizeof(Node));
        q->data = value;
        q->next = p->next;
        p->next = q;
}

/*链表的插入(在指定位置之后插入)*/
void behind_insert(Node *head, int position, int value)
{
        Node *p = head;
        Node *q = NULL;
        int i = 0;
        while(p && i++ < position)
        {
                p = p->next;
        }
        q = (Node *)malloc(sizeof(Node));
        q->data = value;
        q->next = p->next;
        p->next = q;
}