이 코드 주석 부탁드립니다.

[ㅁㅁㅁㅁ(27.117)]

#include<stdio.h>
#include<string.h>
#include<stdlib.h>

struct _node {
   int sNumber;
   char sName[20];
   char sCity[20];
   struct _node* prev;
   struct _node* next;
}typedef NODE;
struct _list {
   int size;
   NODE* head;
   NODE* end;
}typedef DLL;
typedef NODE* pNode;

pNode makeNode ( int number, char * name, char * city );
void printList ( pNode start );
void initialize ( DLL *dl );
void append ( DLL *l, int a, char *b, char *c );
int search ( pNode t, int number );
pNode deleteNode( pNode list, int n );

int main (){
   int num;
   DLL list;
   int index;
   initialize ( &list );
   int searchNum;
   int inputNum;
   char inputName[20];
   char inputReg[20];

   append ( &list, 201201496, "Kwon tae won", "Kimpo" );
   append ( &list, 201201234, "Kim han dong", "Seoul" );
   append ( &list, 201204567, "Kim min kyo", "Busan" );
   append ( &list, 201201496, "Park ji sung", "Daejeon" );

   while ( 1 ){
      printf ( "1.search, 2.append, 3.delete, 4.output, 5.exit\n" );
      printf ( "하실 명령을 입력해주세요:" );
      fflush ( stdin );
      scanf ( "%d", &num );
      switch ( num )
      {
      case 1:
         printf ( "검색항 학번을 입력해주세요:" );
         scanf ( "%d", &searchNum );
         index = search ( list.head, searchNum );
         if ( index != -1 )
            printf ( "index of %d:%d\n", searchNum, index );
         else
            printf ( "Not found!\n" );
         continue;

      case 2:
         printf ( "추가할 학생의 학번을 입력해주세요:" );
         scanf ( "%d", &inputNum );
         printf ( "추가할 학생의 이름을 입력해주세요:" );
         scanf("%s", &inputName);
         //scanf로 입력을 받을시, 공백을 처리하지 못하기에, gets을 이용해서 줄 입력을 받는다.
         //이전 버퍼에 있던 값을 지우기 위해 stdin을 flush해준다.

         printf ( "추가할 학생의 주소를 입력해주세요:" );
         scanf ( "%s", &inputReg );
         append ( &list, inputNum, inputName, inputReg );
         continue;
      case 3:
         printf ( "삭제할 학생의 학번을 입력해주세요:" );
         scanf ( "%d", &searchNum );
         list.head = deleteNode ( list.head, searchNum );
        
         continue;
      case 4:
         printList ( list.head );
         continue;
      case 5:
         printf ( "종료합니다" );
         return 0;
      }

   }

}
void printList ( pNode start )
{
   while ( start != NULL )
   {
      printf ( " ss\n", start->sNumber, start->sName, start->sCity );
      start = start->next;
   }
   printf ( "\n" );
}

void initialize ( DLL *dl ){
   dl->size = 0;
   dl->head = NULL;
   dl->end = NULL;
}

pNode makeNode ( int number, char * name, char * city ){

   pNode temp;
   temp = ( pNode ) malloc ( sizeof( NODE ) );
   temp->sNumber = number;
   strcpy ( temp->sName, name );
   strcpy ( temp->sCity, city );
   temp->prev = NULL;
   temp->next = NULL;
   return temp;

}

void append ( DLL *l, int a, char *b, char *c ){
   pNode temp;
   temp = makeNode ( a, b, c );

   if ( l->size == 0 || l->head == NULL ){
      l->head = temp;
      l->end = temp;
   }
   else
      l->end->next = temp;

   temp->prev = l->end;
   l->end = temp;
   l->size++;
}

int search ( pNode t, int number ){
   int index = 0;
   while ( t != NULL ){
      if ( t->sNumber == number )
         return index;
      t = t->next;
      index++;
   }
   return -1;

}

pNode deleteNode( pNode t, int number )
{
   pNode originalHead = t;
  
   int index = 0;
   pNode target = NULL;
  
   while ( t != NULL ){
      if ( t->sNumber == number )
      {
         target = t;
         break;
      }
      t = t->next;
      index++;
   }
  
   if ( target == NULL ){
      printf ( "Not found!\n" );
      return NULL;
   }

   if ( index == 0 )
   {
      pNode returnVal = target->next;
      free ( target);
      return returnVal;
     
   }
  
   else
   {
      if ( target->next == NULL ){
         target->prev->next = NULL;
         free ( target );
         return originalHead;
      }
      else
      {
         pNode temp = target->prev;
         target->prev->next = target->next;
         target->next->prev = temp;
         free ( target );
         return originalHead;
      }

   }

}