编程实现单链表存储结构及其基本运算的设计方法，主要包括以下功能：

 　　初始化单链表H（H为单链表头指针）

 　　依次采用尾插法插入’a’,’b’,’c’,’d’,’e’五个字符元素

 　　输出单链表H

 　　输出单链表H的长度

 　　判断单链表H是否为空

 　　输出单链表H的第三个元素

 　　输出单链表H中字符元素’d’的位置

 　　在第四个元素位置上插入字符元素’f’

 　　输出单链表H

 　　删除单链表H的第3个元素

 　　输出单链表H

 　　释放并销毁单链表H-Programming a single linked list storage structure and basic operation of the design methods, including the following features: 　initialization single chain H (H is a single list head pointer) 　turn tail interpolation using insert ' a' , ' b' , ' c'　, ' d' , ' e'　five characters in length single chain H output element 　　　output of single chain H H determine whether singly linked list is empty 　single chain H output of the third element 　output single chain H characters element ' d'　position 　insert characters element in the fourth position on the element ' f'　　　output single chain H single chain H delete the first three elements of a single chain H output 　　release and destroy a single chain H