int countcs(struct ListNode *head)
{
    struct ListNode *p;
    p=head;   //p指针指向第一个元素（注意本题的head链表没有头结点）
    int count=0;  //计算机专业学生人数
    while(p!=NULL)  //如果p指针指向的结点存在
    {
        if(p->code[1]=='0'&&p->code[2]=='2')   //如果是计算机专业学生
           count++;          //count加1
        p=p->next;  //p指针后移
    }
    return count;  
}

a.c: In function ‘createlist’:
a.c:17:5: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result]
     scanf("%s", s);
     ^~~~~~~~~~~~~~
a.c:24:9: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result]
         scanf("%s", s);
         ^~~~~~~~~~~~~~

LinkList MaxP(LinkList L)
{
    LinkList maxp,p;
    maxp=p=L->next; //定位指针p指向开始结点，并设置开始结点为最大值结点
    while(p!=NULL)
    {
        if(p->data > maxp->data) //如果p指向的当前结点值大于maxp
            maxp=p; //记录最大值结点
        p=p->next;  //后移定位指针p
     } 
    return maxp;  
}

a.c: In function ‘main’:
a.c:31:11: warning: unused variable ‘e’ [-Wunused-variable]
  ElemType e;
           ^
a.c: In function ‘Create’:
a.c:46:2: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&e);
  ^~~~~~~~~~~~~~
a.c:53:3: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",&e);
   ^~~~~~~~~~~~~~

struct ListNode *createlist() //尾插入法创建链表
{
    int i,x;
    struct ListNode  *p,*head; 
    head=(struct ListNode*)malloc(sizeof(struct ListNode)); 
      //创建带头结点的空单链表
    p=head;    //p定位指针指向最后结点
    scanf("%d",&x);    //读取第一个元素
    while(x!=-1)
    {        
        p->next=(struct ListNode*)malloc(sizeof(struct ListNode));   //创建新结点插入最后结点后面
        p=p->next;         //p移动到新尾结点
        p->data=x;       //数据x存入新结点
        scanf("%d",&x);   //再读取一个元素值存入x
    }
    p->next=NULL;
    return head->next;        //返回创建好的链表第一个结点地址 
}

struct ListNode *deleteeven(struct ListNode *head) //head链表不带头结点 
{
    struct ListNode *p,*r;  //p定位指针，r指向被删的结点
    while(head && head->data % 2==0)
    {  //如果当前第一个结点值是偶数，则删除
        r=head; head=head->next; free(r); 
    }
    p=head; //定位p指针指向第一个结点，如果结点存在，则值是奇数
    while(p && p->next)  
    {
        if(p->next->data % 2==0)  //如果p的下一个结点值是偶数，则删除 
        {
            r=p->next; p->next=r->next; free(r);
        }
        else p=p->next;  //如果下一个结点是奇数，则p后移 
    }
    return head;
}

a.c: In function ‘createlist’:
a.c:35:9: warning: unused variable ‘i’ [-Wunused-variable]
     int i,x;
         ^
a.c:40:5: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&x);    //读取第一个元素
     ^~~~~~~~~~~~~~
a.c:46:9: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d",&x);   //再读取一个元素值存入x
         ^~~~~~~~~~~~~~

#include<stdio.h>
#include<stdlib.h>

typedef struct LNode{
    int data;
    struct LNode* next;
}LNode,*Linklist;  //单链表定义

//函数声明如下
Linklist CreateList();
void Insert(Linklist L,int e); 
void PrintL(Linklist L);

int main()
{
    Linklist L=CreateList(); //尾插法创建有序单链表L
    int e;
    scanf("%d",&e);  //读取待插入的元素e
    Insert(L,e);  //元素e插入到链表L里，保持L有序
    PrintL(L); //显示打印链表元素
}

Linklist CreateList()   //尾插入法创建链表
{
    int n,i,x;
    Linklist p;
    scanf("%d",&n);    //读取链表结点个数
    Linklist head=(LNode*)malloc(sizeof(LNode));   //创建带头结点的空单链表
    p=head;    //p定位指针指向最后结点
    for(i=1;i<=n;i++)
    {
        scanf("%d",&x);   //读取一个元素值存入x
        p->next=(Linklist)malloc(sizeof(LNode));   //创建新结点插入最后结点后面
        p=p->next;         //p移动到新尾结点
        p->data=x;       //数据x存入新结点
    }
    p->next=NULL;
    return head;        //返回创建好的链表
}

void Insert(Linklist L,int e)//e插入有序链表L，保持链表有序
{
    Linklist p,q; //p保存待插入结点位置，q保存p的前驱结点
    p=L->next; //初始化p指向开始结点 
    q=L;  //初始化q指向头结点 
    while(p&&p->data <= e) //找到第一个值大于e的结点，插入在该节点之前
    {
        p=p->next; q=q->next;    //前驱q，当前p定位指针后移
    }
    Linklist s=(LNode*)malloc(sizeof(LNode));   //创建新结点
    s->data=e; s->next=NULL;
    s->next=p; q->next=s;     //新结点插入到p之前，q之后

}

void PrintL(Linklist L)  //显示打印所有链表元素
{
    Linklist p=L->next;  //p指针指向第一个元素
    while(p!=NULL)
    {
        printf(" %d",p->data);   //打印p指向的元素值
        p=p->next;       //指针后移
    } 
} 

a.c: In function ‘main’:
a.c:18:5: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&e);  //读取待插入的元素e
     ^~~~~~~~~~~~~~
a.c: In function ‘CreateList’:
a.c:27:5: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&n);    //读取链表结点个数
     ^~~~~~~~~~~~~~
a.c:32:9: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d",&x);   //读取一个元素值存入x
         ^~~~~~~~~~~~~~