Moi người giúp e xem hàm chèn của e sai đâu với !(DANH SACH LIEN KET DON)

Moi người giúp e xem hàm chèn của e sai đâu với !(DANH SACH LIEN KET DON)

#include <conio.h>
#include <stdio.h>
#include <iostream>
#include <string.h>
 using namespace std ;

 struct SV{
    char ma[30];
    char ten[30];
    int tuoi;
 };
struct Node{
    SV data;
    struct Node *pnext;
};
typedef struct Node NODE;
struct List{
    NODE *phead;
    NODE *ptail;
};
typedef struct List LIST;
NODE* GetNode(SV x)//tao mot nut new
{
    NODE *p=new(NODE);
    if(p==NULL)
        return NULL;
    else
    {
        p->data=x;//lay data gan vao x
        p->pnext=NULL;
        return p;
    }
}
void init(LIST &l)
{
    l.phead=l.ptail=NULL;
}
void input (SV &x)
{
    cout<<"
Nhap MSSV: ";  fflush(stdin); gets(x.ma);
    cout<<"
Nhap ten: ";  fflush(stdin); gets(x.ten);   
    cout<<"
Nhap tuoi: ";cin>>x.tuoi;
}
 void chencuoi(LIST &l,NODE *p)
 {
     if(l.phead==NULL)
        l.phead=l.ptail=p;
    else
    {
        l.ptail->pnext=p;
        l.ptail=p;
    }
 }
void nhap(LIST &l)
{
    SV x;
    char kt;   
    printf("
Nhan phim bat ki de tiep tuc nhap.");
    printf("
Nhan 0 de dung nhap.");
    do
    {
        kt=getch();
        if(kt=='0')  break;
        input(x);
        NODE *p=GetNode(x);
        chencuoi(l,p);
    } while (1);
}
void output (SV x)
{
     cout<<"MA SINH VIEN:"<<x.ma<<endl;
     cout<<"TEN SINH VIEN:"<<x.ten<<endl;
    cout<<"TUOI SINH VIEN:"<<x.tuoi<<endl;
}
void xuat (LIST l)
{
    NODE *p;
    p=l.phead;
    while(p!=NULL)
    {
        output(p->data);
        cout<<"<----------------------------->"<<endl;
        p=p->pnext;
    }
}
void chendau(LIST &l,NODE *p)
{
    if(l.phead==NULL)
        l.phead=l.ptail=p;
    else
        p->pnext=l.phead;
        l.phead=p;
}
void nhapchendau(LIST &l)
{
    SV x;
    char kt;   
    printf("
Nhan phim bat ki de chen dau.");
    printf("
Nhan 0 de dung nhap.");
    do
    {
        kt=getch();
        if(kt=='0')  break;
        input(x);
        NODE *p=GetNode(x);
        chendau(l,p);
    } while (1);	
}
 // chen vi tri bat ki tru dau va  cuoi
 void chen(LIST &l,NODE *p)
 {
 	char a[5];
 	cout<<"Nhap vi tri muon chen";fflush(stdin);
 	cin>>a;
     NODE  *k;
     while(k)
     {
         if(!strcmp(k->data.ma,a))// tim node muon chen vao sau no
           {
           NODE *g;
            g=k->pnext;//g hien tai dang la k;lay k tro sang node sau node chuan bi chen
            k->pnext=p;//lay k tro sang node chuan bi chen
            p->pnext=g;//NOde chuan chuan bi chen tro sang cai node deo tiep the
           }
           return;
     }

 }
 void nhapchentuyy(LIST &l)
 {
     SV x;
    char kt;   
    printf("
Nhan phim bat ki de bat dau chen tuy y.");
    printf("
Nhan 0 de dung nhap.");
    do
    {
        kt=getch();
        if(kt=='0')  break;
        input(x);
        NODE *p=GetNode(x);
        chen(l,p);
    } while (1);		
 }
 //xoa dau
 void xoadau(LIST &l)
 {
     NODE *p=l.phead;
     l.phead=l.phead->pnext;
     delete p;
 }
 //xoa cuoi
 void xoacuoi(LIST &l)
 {
    NODE *p;
    for(NODE *k=l.phead;k;k=k->pnext)
    {
        if(k==l.ptail)
        {
            l.ptail=p;// t gan truoc p cai node cuoi i
            p->pnext=NULL; //cat lien ket giua node p va node k
            delete k;
            return;
        }
        p=k;
    }
 }
 //xoa vi tri bat ki
 void xoa(LIST &l)
 {
 	char a[5];
 	cout<<"Nhap vi tri can xoa:";fflush(stdin);
 	cin>>a;
     NODE *g;
     for(NODE *k=l.phead;k;k=k->pnext)
     {
        if(!strcmp(k->data.ma,a))
          {
              g=k->pnext;
              k->pnext=g->pnext;
              delete g;
              return;
          }

     }
 }
 
 main()
 {  LIST l; SV x;
 	init(l);
     nhap(l);
   	 cout<<"<-----------------Danh sach sau khi nhap------------------------>"<<endl;
     xuat(l);
    /* xoadau(l);
     cout<<"<-----------------Danh sach sau khi xoa------------------------>"<<endl;
    xuat(l);
    xoa(l);
    cout<<"<-----------------Danh sach sau khi xoa------------------------>"<<endl;
    xuat(l);
    nhapchendau(l);
    cout<<"<-----------------Danh sach sau khi chen SV vao dau------------------------>"<<endl;
    xuat(l);*/
    nhapchentuyy(l);
    cout<<"<-----------------Danh sach sau khi chen SV vao tuy y------------------------>"<<endl;
    xuat(l);
     getch();

 }