2018-04-12

how to write list in c

List.h

#ifndef _List_H

#define _List_H

struct Node;

typedef struct Node *PtrToNode;

typedef PtrToNode List;

typedef PtrToNode Position;

List MakeEmpty(List L);
int IsEmpty(List L);
int IsLast(Position P,List L);
Position Find(ElementType X,List L);
void Delete(ElementType X,List L);
Position FindPrevious(ElementType X,List L);
void Insert(ElementType X,List L,Position P);
void DeleteList(List L);
Position Header(List L);
Position First(List L);
Position Advance(Position P);
ElementType Retrieve(Position P);
#endif   /*_List_H */

List.c

#include "List.h"
#include <stdlib.h>
#include "fatal.h"

struct Node
{
    ElementType Element;
    Position Next;
    };
List MakeEmpty(List L){
if(L !=NULL)
DeleteList(L);
L=malloc(sizeof(struct Node));
if(L==NULL)
FatalError("Out of memory!");
L->Next = NULL;
return L;
}

int IsEmpty(List L){
return L->Next == NULL;
}

 int IsLast(Position P,List L){
return P->Next==NULL;
}

Position Find(ElementType X,List L){
  Position P;
  P=L->Next;
  while(P!=NULL && P->Element != X)
  P=P->Next;
  return P;
}

void Delete(ElementType X,List L){
Position P,TmpCell;
P = FindPrevious(X,L);
if(!IsLast(P,L)){
TmpCell = P->Next;
P->Next = TmpCell->Next;
free(TmpCell);
}
}

Position FindPrevious(ElementTpye X,List L){
  Position P;
  P=L;
  while(P->Next !=NULL && P->Next->Element != X)
    P= P->Next;
  return P;
}

void Insert(ElementType X,List L,Position P){
  Position TmpCell;
  TmpCell = malloc(sizeof(struct Node));
  if(TmpCell == NULL)
    FatalError("Out of space!!!");
  TmpCell->Element = X;
 TmpCell->Next = P->Next;
  P->Next = TmpCell;
}

if 0

void DeleteList(List L)
{
Position P;
P = L->Next;
L->Next=NULL;
while(P!=NULL)
{
free(P);
P= P->Next;
}
}

endif

void DeleteLIst(List L)
{
  Position P,Tmp;
  P=L->Next;
  L-Next =NULL;
  while(P!=NULL){
    Tmp = P->Next;
    free(P);
    P=Tmp;
  }
}

Position Header(List L){
  return L;
}

Position First(List L){
  return L->Next;
}

Position Advance(Position P){
  return P->Next;
}

ElementType Retrieve(Position P)
{  
  return P->Element;
}

fatal.h

#include<stdio.h>
#include<stdlib.h>
#define Error(Str) FatalError(Str)
#define FatalError(Str) fprintf(stderr,"%s\n",Str),exit(1)