Question

C语言一道题目，求解

题目是：把一个链表按反序排序，即将原链头当作链尾，原链尾当作链头。将链表的数据保存在文中，并能读取出来，用函数实现。

我把程序写成如下了，可是为什么保存不了呢？请大虾指教并改成符合题目的程序：

#include "stdio.h"
#include<malloc.h>
struct stu
{
int num;
struct stu *next;
};

void main()
{
FILE *in,*out;
char infile[100],outfile[100];
printf("Enter the infile name:\n");
scanf("%s",infile);
printf("Enter the outfile name:\n");
scanf("%s",outfile);
if((in=fopen(infile,"r"))==NULL)
{
printf("cannot open infile\n");
exit(0);
}

if((out=fopen(outfile,"w"))==NULL)
{
printf("cannot open outfile\n");
exit(0);
}

{
int len=1,i;
struct stu *p1,*p2,*head,*new,*newhead;
p1=p2=head=(struct stu *) malloc(sizeof(struct stu));
printf("input number(0:list end):");
scanf("%d",&p1->num);
while(p1->num!=0)
{
p1=(struct stu *)malloc(sizeof(struct stu));
printf("input number(0:list end):");
scanf("%d",&p1->num);
if(p1->num==0)
p2->next=NULL;
else
{
p2->next=p1;
p2=p1;
len++;
}

}
p1=head;
printf("\noriginal list:\n");
do
{
printf("%4d",p1->num);
if(p1->next!=NULL);
p1=p1->next;
}while(p1->next!=NULL);
printf("%4d",p1->num);

for(i=0;i<len;i++)
{
p2=p1=head;
while(p1->next!=NULL)
{
p2=p1;
p1=p1->next;
}
if(i==0)
newhead=new=p1;
else
new=new->next=p1;
p2->next=NULL;
}

printf("\n\new list:\n");
p1=newhead;
for(i=0;i<len;i++)
{
printf("%4d",p1->num);
p1=p1->next;
}
printf("\n");
}

while(! feof(in)) fputc(fgetc(in),out);
fclose(in);
fclose(out);
}

Answer 1

C语言一道题目，求解
悬赏分：0 - 离问题结束还有 14 天 23 小时
题目是：把一个链表按反序排序，即将原链头当作链尾，原链尾当作链头。将链表的数据保存在文中，并能读取出来，用函数实现。

我把程序写成如下了，可是为什么保存不了呢？请大虾指教并改成符合题目的程序：

#include "stdio.h"
#include<malloc.h>
struct stu
{
int num;
struct stu *next;
};

void main()
{
FILE *in,*out;
char infile[100],outfile[100];
printf("Enter the infile name:\n");
scanf("%s",infile);
printf("Enter the outfile name:\n");
scanf("%s",outfile);
if((in=fopen(infile,"r"))==NULL)
{
printf("cannot open infile\n");
exit(0);
}

if((out=fopen(outfile,"w"))==NULL)
{
printf("cannot open outfile\n");
exit(0);
}

{
int len=1,i;
struct stu *p1,*p2,*head,*new,*newhead;
p1=p2=head=(struct stu *) malloc(sizeof(struct stu));
printf("input number(0:list end):");
scanf("%d",&p1->num);
while(p1->num!=0)
{
p1=(struct stu *)malloc(sizeof(struct stu));
printf("input number(0:list end):");
scanf("%d",&p1->num);
if(p1->num==0)
p2->next=NULL;
else
{
p2->next=p1;
p2=p1;
len++;
}

}
p1=head;
printf("\noriginal list:\n");
do
{
printf("%4d",p1->num);
if(p1->next!=NULL);
p1=p1->next;
}while(p1->next!=NULL);
printf("%4d",p1->num);

for(i=0;i<len;i++)
{
p2=p1=head;
while(p1->next!=NULL)
{
p2=p1;
p1=p1->next;
}
if(i==0)
newhead=new=p1;
else
new=new->next=p1;
p2->next=NULL;
}

printf("\n\new list:\n");
p1=newhead;
for(i=0;i<len;i++)
{
printf("%4d",p1->num);
p1=p1->next;
}
printf("\n");
}

while(! feof(in)) fputc(fgetc(in),out);
fclose(in);
fclose(out);
}