您正在尝试创建存储整数或字符串元素的通用列表迭代器。我正在尝试测试它调用IteratorG advance(IteratorG it, int n)函数的情况，该函数接收列表it和if { {1}}是一个正整数，它向第一个元素前进（移动）n次。如果n为负，它向列表中的最后一个元素前进n次。然后将元素复制到新创建的列表中n并返回列表。如果无法前进n次，则该函数返回NULL。
在下面的测试用例中，在测试用例3中对此进行了测试。
但是，它正在响应分段故障错误，我尝试使用gdp来诊断问题，我怀疑它来自行lis的提前功能
这是推进功能：
add(lis,&(tem->value));我正在使用Linux环境，错误是结果的指示。测试它所需的其余函数（在测试代码下的测试用例3中测试）应该正常工作。这是整个程序的代码：
IteratorG advance(IteratorG it, int n){
int zero;
zero=0;
IteratorG lis;
lis = malloc(sizeof (struct IteratorGRep));
assert (lis != NULL);
lis->numofit = 0;
lis->head = NULL;
lis->tail = NULL;
lis->curr = NULL;
Node *tem;
if ((tem = malloc(sizeof(Node))) == NULL) {
return 0;
}
if(n<0 && distanceFromStart(it)!=0 )
{
for(tem=it->curr;n!=zero;it->curr=it->curr->prev)
{
add(lis,&(tem->value));
zero++;
}
return lis;
}
if(n>0 && distanceToEnd(it)!=0)
{
for(tem=it->curr;n!=zero;it->curr=it->curr->next)
{
add(lis,&(tem->value));
zero++;
}
return lis;
}
//To be implemented
//move forward by n times
return NULL;
}
这是代码的头文件：
#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
#include "iteratorG.h"
typedef struct Node {
void *value; // value of thee list item
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;
/*
//Your functions below ....
*/
IteratorG newIterator(ElmCompareFp cmpFp, ElmNewFp newFp, ElmFreeFp freeFp){
IteratorG newit;
if ((newit = malloc(sizeof (struct IteratorGRep)))==NULL)
{
printf("Error...! \n");
}
//assert (newit != NULL);
newit->numofit = 0;
newit->head = NULL;
newit->tail = NULL;
newit->curr = NULL;
newit->cmpElm=cmpFp;
newit->newElm=newFp;
newit->freeElm=freeFp;
return newit;
// implemented function here and changed return value
}
int add(IteratorG it, void *vp){
Node *temp;
if ((temp = malloc(sizeof(Node))) == NULL) {
return 0;
}
Node *tempe;
if ((temp = malloc(sizeof(Node))) == NULL) {
return 0;
}
temp->value = it->newElm(vp);
//temp->next=NULL;
if(it->curr==NULL)
{
//temp->next=it->curr;
it->head=it->tail=temp;
it->curr=temp;
}
else
{
tempe=it->curr;
tempe->prev=temp;
temp->next=tempe;
it->curr=tempe;
it->curr=temp;
it->head=temp;
}
//it->tail=it->head=it->curr;
return 1;
}
int hasNext(IteratorG it){
if(it->curr->next==NULL)
{
return 0;
}
// check if theres next element/node
return 1;
}
int hasPrevious(IteratorG it){
if(it->curr->prev!=NULL)
{
return 1;
}
// check if theres previous element/node
return 0;
}
void *next(IteratorG it){
Node *tempo;
if(it->curr->next==NULL)
{
return NULL;
}
tempo=it->curr;
it->curr=it->curr->next;
// implemented function here
return tempo->value;
}
void *previous(IteratorG it){
Node *tempor;
tempor=it->curr;
if(tempor->prev==NULL)
{
return NULL;
}
tempor=it->curr->prev;
it->curr=it->curr->prev;
//tempor=it->curr;
// move to next node in list
return tempor->value;
}
int del(IteratorG it){
if(it->curr->prev!=NULL)
{
Node *temp_curr=it->curr;
Node *temp_prev=it->curr->prev->prev;
temp_curr->prev=temp_prev;
temp_prev->next=temp_curr;
return 1;
}// delete previous node from list
else
return 0;
}
int set(IteratorG it, void *vp){
if(it->curr->prev!=NULL)
{
it->curr->prev->value=vp;
return 1;
}
// change previous node value with new
return 0;
}
IteratorG advance(IteratorG it, int n){
int zero;
zero=0;
IteratorG lis;
lis = malloc(sizeof (struct IteratorGRep));
assert (lis != NULL);
lis->numofit = 0;
lis->head = NULL;
lis->tail = NULL;
lis->curr = NULL;
Node *tem;
if ((tem = malloc(sizeof(Node))) == NULL) {
return 0;
}
if(n<0 && distanceFromStart(it)!=0 )
{
for(tem=it->curr;n!=zero;it->curr=it->curr->prev)
{
add(lis,tem);
zero++;
}
return lis;
}
if(n>0 && distanceToEnd(it)!=0)
{
for(tem=it->curr;n!=zero;it->curr=it->curr->next)
{
add(lis,&(tem->value));
zero++;
}
return lis;
}
//To be implemented
//move forward by n times
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;// reverse elements of whole list
}
IteratorG find(IteratorG it, int (*fp) (void *vp) ){
// To be implemented
// Find elements of vp in list after current position and put in new list.return the list.
return NULL;
}
int distanceFromStart(IteratorG it){
Node *c=it->curr;
int count=0;
while(c->prev!=NULL)
{
c=c->prev;
count++;
}
return count;
// count number of elements from start of list to current position
}
int distanceToEnd(IteratorG it){
Node *cu=it->curr;
int count=0;
while(cu->next!=NULL)
{
cu=cu->next;
count++;
}
return count;
// count number of elements from end of list to current position
}
void reset(IteratorG it){
while(it->curr->prev!=NULL)
{
it->curr=it->curr->prev;
}
return;
// move current position to start of list
}
void freeIt(IteratorG it){
assert(it != NULL);
Node *curr, *prev;
curr = it->head;
while (curr != NULL) {
prev = curr;
curr = curr->next;
// free(prev->value);
free(prev);
}
free(it); // free items
}
其中一个功能尚未实现，并在代码本身中指出。但我想这可能不是问题的根源。
编辑： 下面是测试用例代码。仅在上面的程序中，测试用例代码中没有错误：
#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