양 방향 링크 찾기, 삭제, 삽입 노드

#include
#include
typedef struct student
{
    int num;
    struct student *next;
    struct student *prior;
}LDstudent,*LDPstudent;
//-------------    
void InitLink(LDPstudent *phead)
{
    *phead=NULL;
    LDPstudent ptr;
    LDPstudent r=ptr;//          
    int n;
    printf("please input num of student:
");
    scanf("%d",&n);
    while(n>0)
    {
        ptr=malloc(sizeof(LDstudent));
        ptr->num=n;

/*      ptr->next=*phead;//      
        ptr->prior=NULL;
        if(*phead!=NULL)
            (*phead)->prior=ptr;
        *phead=ptr;
*/
                            //   
                            ptr->next=NULL;
                            if(*phead==NULL)
                            {   ptr->prior=NULL;
                                *phead=ptr;}
                            else

                            {   ptr->prior=r;
                                r->next=ptr;}

                            r=ptr;
        printf("please input num of student:
");
        scanf("%d",&n);
    }


}
 //-------------    
void printf_link(LDstudent *ptr)
{
    LDPstudent p1=ptr;
    printf("    :
");
    while(p1!=NULL)
    {
        printf("%d\t",p1->num);
        p1=p1->next;
    }
    printf("
");
    printf("    :
");
    p1=ptr;
    while(p1->next!=NULL)
        p1=p1->next;
    while(p1!=NULL)
    {
        printf("%d\t",p1->num);
        p1=p1->prior;
    }printf("
");
}
                     //-----------    
unsigned int ListLength(LDPstudent ptr)
{
    unsigned int l=0;
    while(ptr!=NULL)
    {   ptr=ptr->next;
        l++;}
    return l;
}
            //-------------------     
LDPstudent ListLocate(LDPstudent ptr,int i)
{
    int j=1;
    while(ptr!=NULL&&jnext;
        j++;
    }
    if(j==i)return ptr;
    else return NULL;
}
//-----------------------    
LDPstudent ListLocate2(LDPstudent ptr,int i)
{
    while(ptr!=NULL)
    {
        if(ptr->num==i)return ptr;
        else ptr=ptr->next;}
        return ptr;
}
//-------------------------      

void ListInsert(LDPstudent ptr,int i,int j)
{
    LDPstudent p1=ListLocate(ptr,i);
    if(p1==NULL)
    {   printf("  %d  ,error!
",i);return;}
    else{
        LDPstudent p2=malloc(sizeof(LDstudent));
        p2->num=j;
        p2->prior=p1;
        if(p1->next!=NULL)
        {   p2->next=p1->next;
            p1->next->prior=p2;}
        else p2->next=NULL;
        p1->next=p2;}
        printf("----------     ----------:
");
        printf_link(ptr);
}

//-------------------------      

void ListInsert2(LDPstudent ptr,int i,int j)
{
    LDPstudent p1=ListLocate(ptr,i);
    if(p1==NULL)
    {   printf("  %d  ,error!
",i);return;}
    else{
        LDPstudent p2=malloc(sizeof(LDstudent));
        p2->num=j;
        p2->next=p1;
        p2->prior=p1->prior;
        if(p1->prior!=NULL)
        {   p1->prior->next=p2;}
        else ptr=p2;//          ;
        p1->prior=p2;}
        printf("----------     ----------:
");
        printf_link(ptr);
}

//--------------------------      

void ListInsert3(LDPstudent ptr,int i,int j)
{
    LDPstudent p1=ListLocate2(ptr,i);
    if(p1==NULL)
    {   printf("     ,error!
");return;}
    else{
        LDPstudent p2=malloc(sizeof(LDstudent));
        p2->num=j;
        p2->prior=p1;
        if(p1->next!=NULL)
        {   p2->next=p1->next;
            p1->next->prior=p2;}
        else p2->next=NULL;
        p1->next=p2;}
        printf("----------     ----------:
");
        printf_link(ptr);
}
//---------------------------     
void ListInsert4(LDPstudent ptr,int i,int j)
{
    LDPstudent p1=ListLocate2(ptr,i);
    if(p1==NULL)
    {   printf("     ,error!
");return;}
    else{
        LDPstudent p2=malloc(sizeof(LDstudent));
        p2->num=j;
        p2->next=p1;
        p2->prior=p1->prior;
        if(p1->prior!=NULL)
        {   p1->prior->next=p2;}
        else ptr=p2;//          ;
        p1->prior=p2;}
        printf("----------    ----------:
");
        printf_link(ptr);
}
//-----------------------------     
void ListDelete(LDPstudent ptr,int i)
{
    LDPstudent p1=ListLocate2(ptr,i);

    if(p1==NULL)
    {   printf("   （ ）  ,error!
");return;}
    else
    {
        if(p1->prior==NULL&&p1->next!=NULL)
        {
            p1->next->prior=NULL;ptr=p1->next;//     
        }
        else if(p1->next==NULL&&p1->prior!=NULL)
        {
            p1->prior->next=NULL;
        }
        else if(p1->prior==NULL&&p1->next==NULL)
        {   ptr=NULL;   }
        else
        {
            p1->prior->next=p1->next;
            p1->next->prior=p1->prior;
        }
        printf("
------       ：----------
");

        if(ptr==NULL)printf("NULL
");
        else printf_link(ptr);
    }
}

//-----------------------------     
void ListDelete2(LDPstudent ptr,int i)
{
    LDPstudent p1=ListLocate2(ptr,i);

    if(p1==NULL)
    {   printf("   （ ）  ,error!
");return;}
    else
    {
        if(p1->prior==NULL&&p1->next!=NULL)
        {
            p1->next->prior=NULL;ptr=p1->next;//     
        }
        else if(p1->next==NULL&&p1->prior!=NULL)
        {
            p1->prior->next=NULL;
        }
        else if(p1->prior==NULL&&p1->next==NULL)
        {   ptr=NULL;   }
        else
        {
            p1->prior->next=p1->next;
            p1->next->prior=p1->prior;
        }
        printf("
------     ：----------
");

        if(ptr==NULL)printf("NULL
");
        else printf_link(ptr);
    }
}
// -======================   
int main()
{
    LDPstudent head;
    InitLink(&head);

    printf_link(head);//     

    unsigned int l;//    
    l=ListLength(head);
    printf("
  l:%d
",l);

/*  LDPstudent p=ListLocate(head,3);//      
    if(p==NULL)
        printf("no third student
");
    else
        printf("this third is %d
",p->num);

    LDPstudent p2=ListLocate2(head,4);//    
    if(p2==NULL)
        printf("no this student
");
    else
        printf("this is %d
",p2->num);
*/
//  ListInsert(head,3,3333);//      


//  ListInsert2(head,3,2222);//      


//  ListInsert3(head,6,6666);//     


//  ListInsert4(head,6,5555);//     

    ListDelete(head,3);//     
    ListDelete2(head,6);//    

}