#include<iostream.h>
#include<string.h>
struct STUDENT
{
    char num[10];
    int score;
    STUDENT *next;
}

STUDENT *Create()    //新建链表
{
    STUDENT *p,*q,*head;
    int i=1,number;
    cout<<"请输入学生人数:"<<endl;
    cin>>number;
    cout<<"请按学号顺序输入各位同学的学号和成绩!"<<endl;
    head=0;
    while(i<=number)
    {
        p=new STUDENT;
        cout<<"请输入第"<<i<<"位同学的学号和成绩:";
        cin>>p->num;
        cin>>p->score;
        if(head==0)
        {
            head=p;
            q=p;
        }
    else
    {
        q->next=p;q=p;
    }
    i++;
    }
    q->next=0;
    return(head);
}

void Travel(STUDENT *head)    //遍历链表
{
STUDENT *p;
int i=1;
p=head;
cout<<"链表中的数据输出如下:"<<endl;
while(p!=0)
{
    cout<<"第"<<i<<"个节点中的数据为"<<endl;
    cout<<p->num<<" "<<p-score<<endl;
    p=p->next;
    i++;
}
}

STUDENT *Insertnode(STUDENT *head,STUDENT *p)    //在链表中插入一个节点
{
 STUDENT *be,*ne;
 if(head==0)
 {
     head=p;
     p->next=0;
     return(head);
 }
 if(strcmp(head->num,p->num)>=0)
 {
     p->next=head;
     head=p;
     return(head);
 }
 be=ne=head;
 while(ne!=0 && strcmp(ne->num,p->num)<0)
 {
     be=ne;
     ne=ne->next;
 }
 p->next=ne;
 be->next=p;
 return(head);
}

STUDENT *Deletenode(STUDENT *head,char num[])    //在链表中删除一个节点
{
    STUDENT *be,*p;
    if(head==NULL)
    {
        cout<<"链表已经为空，无节点可以删除!"<<endl;
        return(head);
    }
    if(strcmp(head->num,num)==0)
    {
        p=head;
        head=head->next;
        delete p;
    }
    else
    {
        be=p=head;
        while(strcmp(p->num,num)!=0 && p->next!=NULL)
        {
            be=p;
            p=p->next;
        }
        if(strcmp(p->num,num)==0)
        {
            be->next=p->next;
            delete p;
            cout<<"删除了一个节点!"<<endl;
        }
        else
            cout<<"链表中没有找到所要删除的节点!"<<endl;
    }
    return(head);
}

void releaschain(STUDENT *head)         //释放链表
{
    STUDENT *p;
    while(head)
    {
        p=head;
        head=head->next;
        delete p;
    }
}

void main(void)
{
    STUDENT *head,*t;
    char n[10];
    head=Create();
    Travel(head);
    t=new STUDENT;
    cout<<"请输入需要插入同学的学号和成绩:";
    cin>>t->num>>t->score;
    head=Insertnode(head,t);
    Travel(head);
    cout<<"请输入要删除同学的学号:";
    cin>>n;
    head=Deletenode(head,n);
    Travel(head);
    releasechain(head);
}

改过了，struct要有个分号，struct{……}；
最后的main函数的release拼写错误，错误提示为函数没有定义。改过后就可以了