实验三单链表

#include <iostream>  
using namespace std;  
const int N=5;  
struct Std{  
    int date;  
    Std *next;  
}*p,*r;  
class Student{  
private:  
    Std *first;  
    int length;  
public:  
    Student();  
    Student(int a[],int n);  
    ~Student(){}  
    void Insert(int i,int x);  
    int Delete(int i);  
    int Get(int i);  
    int Locate(int x);  
    void Show();  
};  
Student::Student(){  
    first =new Std;  
    first->next=NULL;  
}  
Student::Student(int a[],int n){  
    first=new Std;  
    first->next=NULL;  
    r=first;  
    for (int i=0;i<n;i++){  
        p=new Std;  
        p->date=a[i];  
        r->next=p;  
        r=p;  
    }  
    r->next=NULL;  
    lenght=n;  
}  
void Student::Insert(int i,int x){  
    r=first;  
    int j=0;  
    while (r!=NULL&&j<i-1){  
        r=r->next;  
        j++;  
    }  
    if (r==NULL) throw "位置非法";  
    else {  
        p=new Std;  
        p->next=r->next;  
        p->date=x;  
        r->next=p;  
        length++;  
    }  
}  
int Student::Delete(int i){  
    r=first;  
    int j=0;  
    while (r!=NULL&&j<i-1){  
        r=r->next;  
        j++;  
    }  
    if (r==NULL) throw "位置非法";  
    else {  
        p=r->next;  
        r->next=p->next;  
        delete p;  
        lenght--;  
    }  
    return p->date;  
}  
int Student::Get(int i) {  
    r = first;  
    int j = 0;  
    while (r != NULL && j<i - 1) {  
        r = r->next;  
        j++;  
    }  
    if (r == NULL) throw "位置非法";  
    else   
        p = r;  
    return p->date;  
}  
int Student::Locate(int x) {  
    r = first;  
    int j=0;  
    while (r != NULL) {  
        r = r->next;  
        j++;  
        if (r->date == x) break;  
    }  
    if (r == NULL) throw "位置非法";  
    return j;  
}  
void Student::Show() {  
    r = first;  
    while (r->next!= NULL) {  
        r = r->next;  
        cout << r->date << ' ';  
    }  
    cout<<endl;  
}  
  
int main() {  
    int a[3] = { 90,80,75 };  
    Student S(a, 3);  
    cout << "原表：" << endl;  
    S.Show();  
    cout << "在第3位插入98：" << endl;  
    S.Insert(3, 98);  
    cout << "插入后：" << endl;  
    S.Show();  
    cout << "删除第2位：" << endl;  
    S.Delete(2);  
    cout << "删除后：" << endl;  
    S.Show();  
    cout << "查75分的位置：" << S.Locate(75) << ',' << "查第2位的成绩：" << S.Get(2) << endl;  
    return 0;  
}