一执行到p->next=NULL时，就出现Unhandle exception in 21302.exe:0x0000005:Access Violation

[HQWEIEI]

#include<stdio.h>
typedef struct inlist
{
int data;
struct inlist *next;
}inlist;

inlist *creatlist(inlist *l);
int len_list(inlist *I);


main()
{
inlist *l=malloc(sizeof(inlist));
int x=0,k=0,len=0;
l=creatlist(l);
len=len_list(l);

}
inlist *creatlist(inlist *l)
{
inlist *p=malloc(sizeof(inlist)),
*q=malloc(sizeof(inlist));
int e=0;
p=l;
while(e!=-1)
{
p->next=q;
p=p->next;
scanf("%d",&e);
p->data=e;
q=malloc(sizeof(inlist));

}
p->next=NULL;
free(p);
free(q);
return l;
}
int len_list(inlist *l)
{
inlist *p=malloc(sizeof(inlist));
int i=0;
p=l;
p=p->next;
while(p->next!=NULL) //*一执行到p->next=NULL时，就出现Unhandle exception in 21302.exe:0x0000005:Access Violation 为什么？？？？？
{
i++;
p=p->next;
}


return i;
}

[pengzhixi]

你应该在你创建链表这个函数里面找原因。

[wade_2003]

inlist *creatlist(inlist *l)
{
inlist *p=malloc(sizeof(inlist)),
*q=malloc(sizeof(inlist));
int e=0;
p=l;
while(e!=-1)
{
p->next=q; // 是这里有问题吧
p=p->next;
scanf("%d",&e);
p->data=e;

[peng6sl]

我试了下楼主的代码，主要是所有的malloc(sizeof(inlist))都没有指定类型，应该是（inlist*）malloc(sizeof(inlist))，然后就没什么问题了，我是在unbuntu下编译的

[cattycat]

创建链表的部分不对。

inlist *creatlist(inlist *l)
{
inlist *p=malloc(sizeof(inlist)),
*q=malloc(sizeof(inlist));
q->next=NULL; //先初始化一下
int e=0;
l->next=p;//p=l;
while(e!=-1)
{
p->next=q;
p=p->next;
scanf("%d",&e);
p->data=e;
q=malloc(sizeof(inlist));
q->next=NULL; //加上这个
}
p->next=NULL;
//free(p);
free(q);
return l;
}

[wade_2003]

给你个参考例子

#include <iostream>
#include "malloc.h"
#define LEN sizeof(struct node)
struct node
{
	int m;
	struct node *prev,*next;
};

struct node* create(int n)
{
	struct node *first,*last,*temp;
	first =last = new node;
		first->m = 1;
		first->next = NULL;
		last = first;
	for (int i =2;i<=n;i++)
	{
	   temp =(struct node*)malloc(LEN);
		temp ->m =i;
		temp->next = NULL;
	    last->next =temp;
		temp->prev =last;
		last = temp;
	}
	last->next =first;
	first->prev =last;
	return first;
}
void main()
{
	int n;
	scanf("%d",&n);
	struct node *move,*link,*temp;
	move =link = create(n);

	while(move !=link);
    
	for(int i=0;i<n;i++)
	{
		for(int j=0;j<n;j++)
	   {
		   printf("%d",move->m);
		   move=move->next;
	   }
		move = move->next;
       printf("\n");
	}
	free(move);
}*/

[田暗星]

[Quote=引用 3 楼 peng6sl 的回复:]
我试了下楼主的代码，主要是所有的malloc(sizeof(inlist))都没有指定类型，应该是（inlist*）malloc(sizeof(inlist))，然后就没什么问题了，我是在unbuntu下编译的
[/Quote]

对了，问题找到了

[huanmie_09]

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

typedef struct inlist
{
	int data;
	struct inlist *next;
} inlist;

inlist *creatlist(inlist *l);
int len_list(inlist *I);
void print_list(inlist *l);
void free_list(inlist *l);

int main()
{
	inlist *l=(inlist *)malloc(sizeof(inlist));
	int x=0,k=0,len=0;
	if(l == NULL) {
		exit(1);
	}
	l->next = NULL;
	l=creatlist(l);
	print_list(l);
	len=len_list(l);
	printf("len=%d\n", len);
	free_list(l);
	return 0;
}

inlist *creatlist(inlist *l)
{
	inlist *p = NULL;  //=(inlist *)malloc(sizeof(inlist));
	inlist *q = l;
	//*q=malloc(sizeof(inlist));
	int e=0;
	//p=l;
	while(1)
	{
		//p->next=q;
		//p=p->next;
		scanf("%d",&e);
		if(e == -1) {
			break;
		}
		p=(inlist *)malloc(sizeof(inlist)); 
		if(p == NULL) {
			exit(1);
		}
		p->data=e;
		p->next = NULL;
		q->next = p;
		q = p;		 
	}
	q->next = NULL;
	//free(p);
  	//free(q);
	return l;
}

int len_list(inlist *l)
{
	inlist *p; /*=malloc(sizeof(inlist));*/
	int i=0;
	p=l->next;
  	//p=p->next;
	//while(p->next!=NULL) //*一执行到p->next=NULL时，就出现Unhandle exception in 21302.exe:0x0000005:Access Violation 为什么？？？？？
	while(p != NULL)
	{
		i++;
		p=p->next;
	}
	return i;
}

void print_list(inlist *l)
{
	inlist *p; 
	p=l->next;
	while(p != NULL)
	{
		printf("%d ", p->data);
		p=p->next;
	}
	printf("\n");
}

void free_list(inlist *l)
{
	inlist *p, *q; 
	p = l;
	while(p != NULL)
	{	
		q = p->next;
		free(p);
		p = q;
	}
}