#include<stdio.h>
#include<malloc.h>
struct link
{
    int data;
    struct link *next;
};
struct link* creat()
{
    struct link *head,*tail,*p;
    head=tail=NULL;
    printf("please input one number:\n");
    p=(struct link*)malloc(sizeof(struct link));
    p->next=NULL;
    scanf("%d",&p->data);
    while(p->data!=0)
    {
        if(head==NULL)head=tail=p;
        else
        {
            tail->next=p;
            tail=p;
        }
        p=(struct link*)malloc(sizeof(struct link));
        p->next=NULL;
        scanf("%d",&p->data);
    }
    return(head);
}

output(struct link* head)
{
    int k=0;
    struct link *p;
    p=head;
    while(p!=NULL)
    {   k++;
        printf("the %dTH is %d\n",k,p->data);
        p=p->next;
    }

}
struct link* comein(struct link* head,struct link *newdata)
{
    struct link *p1,*p2;
    p1=head;
    while(p1!=NULL&p1->data>=newdata->data)
    {
        p2=p1;
        p1=p1->next;
    }
    if(!(p1->data>=newdata->data))
    {
        if(p1==head)
            {
            head=newdata;
            newdata->next=p1;
            }
        else
        {
            p2->next=newdata;
            newdata->next=p1;
        }

    }
    else
    {
        p1->next=newdata;
        newdata->next=NULL;
    }
    return(head);
}
struct link *del(struct link *head,int k)
{
    struct link *p1,*p2;
    p1=head;
    while(p1!=NULL&&p1->data!=k)
    {
        p2=p1;
        p1=p1->next;
    }
    if(p1->data==k)
    {
        if(p1==head) head=p1->next;
        else
        {
            p2->next=p1->next;
        }
    }
    return(head);
}
main()
{
    struct link *head,*p;
    int k;
    printf("THE fellow is creat test:\n");
    head=creat();
    output(head);
    printf("THE fellow is COMEIN test:\n");
    printf("please input a newdata:\n");
    p=(struct link *)malloc(sizeof(struct link));
    scanf("%d",&p->data);
    p->next=NULL;
    comein(head,p) ;
    output(comein(head,p));
    printf("the fellow is DEL test:\n");/ *这里没有执行*/
   printf("please input DEL number:");/*这里没有执行*/
    scanf("%d",&k);/*这里没有执行*/
    output(del(comein(head,p),k));/*这里没有执行*/

    getch();
}

问题已经解决！需要在开头加#include<string.h>!希望和我有同样问题的朋友注意……

还要在前面加fflush（stdin）才算真正解决