嘿我正在尝试实现一个通用列表迭代器，它可以存储任何类型的元素。它有其他文件来处理正整数类型和字符串类型。但是，我收到一个错误，指出结构IteratorGRep没有名为'的成员接下来'和'prev'。节点next和prev都已经声明了，这应该工作正常但不确定错误在哪里。我正在使用linux环境，错误是编译时的指示。这里是代码：
#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
#include "iteratorG.h"
typedef struct Node {
char *value; // value of thee list item (string)
struct Node *prev;
// pointer previous node in list
struct Node *next;
// pointer to next node in list
// implemented struct here ..
} Node;
typedef struct IteratorGRep {
int numofit; // count of items in list
Node *head; // first node in list
Node *curr; // current node in list
Node *tail; // last node in list
ElmCompareFp cmpElm;
ElmNewFp newElm;
ElmFreeFp freeElm;
// implemented struct here ..
} IteratorGRep;
/*
// functions below ....
*/
IteratorG newIterator(ElmCompareFp cmpFp, ElmNewFp newFp, ElmFreeFp freeFp){
struct IteratorGRep *it;
it = malloc(sizeof (struct IteratorGRep));
assert (it != NULL);
it->numofit = 0;
it->head = NULL;
it->tail = NULL;
it->curr = NULL;
it->cmpElm=cmpFp;
it->newElm=newFp;
it->freeElm=freeFp;
return it;
// created list
}
int add(IteratorG it, void *vp){
Node *temp=NULL;
temp=it->next;
it->next=vp;
vp->prev=it;
vp->next=temp;
temp->prev=vp;
// Inserts element pointed by 'vp' into list iterator 'it'
return 1;
}
int hasNext(IteratorG it){
if(it->next!=NULL)
{
return 1;
}
// check for any next elements
return 0;
}
int hasPrevious(IteratorG it){
if(it->prev!=NULL)
{
return 1;
}
// check for any previous elements
return 0;
}
void *next(IteratorG it){
if(it->next!=NULL)
{
it=it->next;
Node *curre=it->curr;
return curre;
}
// move to next element
return NULL;
}
void *previous(IteratorG it){
if(it->prev!=NULL)
{
it=it->prev;
Node *curre=it->curr;
return curre;
}
// moves to previous element
return NULL;
}
int del(IteratorG it){
if(it->prev!=NULL)
{
Node *temp_curr=it->curr;
Node *temp_prev=it->prev->prev;
temp_curr->prev=temp_prev;
temp_prev->next=temp_curr;
return 1;
}
// removes previous element from list
if(it->prev==NULL)
{
return 0;
}
}
int set(IteratorG it, void *vp){
if(it->prev!=NULL)
{
Node *store_curr=it->curr;
Node *store_prev=it->prev->prev;
store_curr->prev=vp;
vp->next=store_curr;
store_prev->next=vp;
vp->prev=store_prev;
return 1;
}
// Replaces previous element with the element (*vp)
return 0;
}
IteratorG advance(IteratorG it, int n){
// Advance by n times and return list with n times of elements
// To implement function here and change return value
return NULL;
}
void reverse(IteratorG it){
Node *curr = it->head;
Node *temp = NULL;
while(curr != NULL) {
temp = curr->next;
curr->next = curr->prev;
curr->prev = temp;
curr = temp;
}
temp = it->head;
it->head = it->tail;
it->tail = temp;
// reverses order of list
}
IteratorG find(IteratorG it, int (*fp) (void *vp) ){
// finds elements after current position,append to new list
// To implement function here and change return value
return NULL;
}
int distanceFromStart(IteratorG it){
Node *c=it->curr;
int count=0;
if (c->prev==NULL){
return 0;
}
while(c->prev!=NULL)
{
c=c->prev;
count++;
return count;
}
// counts number of nodes from current position to start of list
}
int distanceToEnd(IteratorG it){
Node *cu=it->curr;
int count=0;
if (cu->next==NULL){
return 0;
}
while(cu->next!=NULL)
{
cu=cu->next;
count++;
return count;
}
// counts number of nodes from current position to end of list
}
void reset(IteratorG it){
it->curr=it->head;
// reset to start of list
return;
}
void freeIt(IteratorG it){
assert(it != NULL);
Node *curr, *prev;
curr = it->first;
while (curr != NULL) {
prev = curr;
curr = curr->next;
free(prev->value);
free(prev);
}
free(it);
// remove nodes in it and free memory
}
这是代码的头文件：
#ifndef LISTITERATORG_H
#define LISTITERATORG_H
#include <stdio.h>
typedef struct IteratorGRep *IteratorG;
typedef int (*ElmCompareFp)(void const *e1, void const *e2);
typedef void *(*ElmNewFp)(void const *e1);
typedef void (*ElmFreeFp)(void *e1);
IteratorG newIterator(ElmCompareFp cmpFp, ElmNewFp newFp, ElmFreeFp freeFp);
int add(IteratorG it, void *vp);
int hasNext(IteratorG it);
int hasPrevious(IteratorG it);
void *next(IteratorG it);
void *previous(IteratorG it);
int del(IteratorG it);
int set(IteratorG it, void *vp);
IteratorG advance(IteratorG it, int n);
void reverse(IteratorG it);
IteratorG find(IteratorG it, int (*fp) (void *vp) );
int distanceFromStart(IteratorG it);
int distanceToEnd(IteratorG it);
void reset(IteratorG it);
void freeIt(IteratorG it);
#endif
其中一个功能尚未实现，并在代码本身中显示。但我猜这可能不是问题的根源。我认为这里没有正确使用节点。