c中的文件问题

[joy_91]

输出结果为read error！16
feof结果怎么会是16呢。。。。为什么会读入不了呢
其中lineinfo为结构体

void main()
{   FILE *fp;
   
	int i=0;
    if ((fp=fopen("F:\data.txt","rb"))==NULL)
	 {printf("cannot open file!");
      exit(0);}
  
		while(!feof(fp))

	{
	 if(fread(&lineinfo[0],sizeof(struct airline),1,fp)!=1)
	{ printf("read error!");
	  printf("%d",feof(fp));
	  exit(0);}
    	}
    fclose(fp);}

[qq120848369]

还没fread就判断feof永远都是false.

[ryfdizuo]

http://www.cplusplus.com/forum/general/22522/
fp=fopen("F:\data.txt","r") 试试

[a707000646]

The feof function returns a nonzero value after the first read operation that attempts to read past the end of the file
The feof routine (implemented both as a function and as a macro) determines whether the end of stream has been reached. When end of file is reached, read operations return an end-of-file indicator until the stream is closed or until fsetpos, fseek, or clearerr is called against it.
feof例程（作为一个函数和宏实现）确定是否已到达流的末尾。当到达文件末尾，读操作返回一个文件结束的指标，直到流关闭或直到fsetpos，FSEEK，或clearerr发生响应。

[selooloo]

你的文件是用fwrite写的吗

[joy_91]

[Quote=引用 1 楼 dizuo 的回复:]
http://www.cplusplus.com/forum/general/22522/
fp=fopen("F:\data.txt","r") 试试
[/Quote]

试过了，还是没有用，结果一样
我想会不会是因为fread无法访问，所以对feof产生影响？
fread又为什么就是无法读出呢

[a707000646]

#include<stdio.h>
struct airline
{
       int a;
       int b;
};
int main()
{   FILE *fp;
    struct airline lineinfo[4];
    lineinfo[0].a = 1;
    lineinfo[0].b = 2;
    lineinfo[1].a = 3;
    lineinfo[1].b = 4;
    int i=2;
    if((fp = fopen("lineinfo.out","wb")) == NULL)
    {
          printf("cannot open file!");
          exit(0);
    }
    fwrite(&lineinfo[0],sizeof(struct airline),1,fp);
    fwrite(&lineinfo[1],sizeof(struct airline),1,fp);
    fclose(fp);
    getchar();
    if ((fp=fopen("lineinfo.out","rb+"))==NULL)
     {printf("cannot open file!");
      exit(0);}
      
        while(!feof(fp))
    {
    fread(&lineinfo[i++],sizeof(struct airline),1,fp);
        }
    printf("%d   %d\n",lineinfo[2].a,lineinfo[2].b);
    printf("%d   %d",lineinfo[3].a,lineinfo[3].b);
    fclose(fp);
    system("pause");
    return 0;
}

[joy_91]

[Quote=引用 2 楼 a707000646 的回复:]
The feof function returns a nonzero value after the first read operation that attempts to read past the end of the file
The feof routine (implemented both as a function and as a macro) determines whe……
[/Quote]

是不是说若没有到结尾就返回任意实数。。。。为什么是16呢

[joy_91]

[Quote=引用 3 楼 selooloo 的回复:]
你的文件是用fwrite写的吗
[/Quote]

fread

[a707000646]

返回非零值 2楼的朋友的帖子我看过了,他那里说的解决方法就是让你改读写方式
测试下,帮助文档上面只说事非零值

[a707000646]

不好意思 我的代码多了个getchar(),记得回车一下

[赵4老师]

推荐使用WinHex软件查看文件原始字节内容。