使用二级指针创建单链表，程序功能菜单如图所示voidshowMenu(){printf("\t\t\t\t\t\t1.使用头插法创建链表\n");printf("\t\t\t\t\t\t2.使用尾插法创建链表\n");printf("\t\t\t\t\t\t3.按序号查找\n");printf("\t\t\t\t\t\t4.按值查找\n");printf("\t\t\t\t\t\t5.按值插入\n");printf("\t\t\t\t\t\t6.按位置插入\n");pri