CFile open的问题

[永远的明日]

CFile中的open怎么用的啊···？
怎么打不开存在的文件？？各位大大帮忙看看下面代码
void down_to_client(SOCKET sa)
{
	int bytes;
	char tem [259]="dir ";
	long file_length;
	int exist = 1;
        char buf[4096];
	char pathname[256];

	 
	memset(buf,0,sizeof(buf)); 
	recv(sa,buf,BUF_SIZE,0);
    memset(&pathname,0,sizeof(pathname));
    strcpy(pathname,dir);
	strcat(pathname,"\\");
	strcat(pathname,buf);
	CFile file;
	
	exist=file.Open(pathname,CFile:: modeRead); //pathname="c:\\a.txt"时，返回值为0，c盘下有这个文件的，当执行完这步，a.txt变为空
                                                           //双击打开提示有程序在使用该文件···
	if(!exist)
	{
		memset(buf,0,sizeof(buf)); 
		DeleteFile(pathname);
		ltoa(0, buf, 10); 
        send(sa,buf,BUF_SIZE,0);
		return ;
	}
	file_length = file.GetLength();
	memset(buf,0,sizeof(buf)); 
	ltoa(file_length, buf, 10); 
	send(sa,buf,BUF_SIZE,0);
	while(1)
	{
		bytes = file.Read(buf,BUF_SIZE);
		if(bytes<=0)break;
		send(sa,buf,bytes,0);
		
	}
	
	
}

[majun01]

CFile的Open()是不支持文本方式读写
http://c.chinaitlab.com/cc/basic/200810/766694.html

[永远的明日]

[Quote=引用 1 楼 majun01 的回复:]
CFile的Open()是不支持文本方式读写
http://c.chinaitlab.com/cc/basic/200810/766694.html
[/Quote]
可为什么下面的又行？？在open之前没打开该文件·

int main()
{
CFile file;
	int exist = 1;
	char pathname[256];
	memset(&pathname,0,sizeof(pathname));
	strcpy(pathname,"c:\\a.txt");
	exist=file.Open(pathname,CFile:: modeRead);//返回值为1
	cout<<exist<<endl;
}

[hityct1]

看msdn，更改一下打开方式：

CFile::modeCreate
Directs the constructor to create a new file. If the file exists already, it is truncated to 0 length.


CFile::modeNoTruncate
Combine this value with modeCreate. If the file being created already exists, it is not truncated to 0 length. Thus the file is guaranteed to open, either as a newly created file or as an existing file. This might be useful, for example, when opening a settings file that may or may not exist already. This option applies to CStdioFile as well


文件用完要Close

[星羽]

memset(buf,0,sizeof(buf));
recv(sa,buf,BUF_SIZE,0);
memset(&pathname,0,sizeof(pathname));
strcpy(pathname,dir);
strcat(pathname,"\\");
strcat(pathname,buf);
CFile file;


你看一下 pathname是不是最后没有字符串结束符？

[zhaohongbo83]

看一下 MSDN 吧

[SearchLife]

mark

[永远的明日]

[Quote=引用 4 楼 Chiyer 的回复:]
memset(buf,0,sizeof(buf));
recv(sa,buf,BUF_SIZE,0);
memset(&pathname,0,sizeof(pathname));
strcpy(pathname,dir);
strcat(pathname,"\\");
strcat(pathname,buf);
CFile file;


你看一下 pathname是不是最后没有字符串结束符？
[/Quote]
应该没有，因为我把pathname直接用"c:\\a.txt"代替也不行··
同时读一文件，写另一个文件应该没问题的吧？？？

[abheyong]

这你都不知道

[nineforever]

CFile默认打开是exclusive的，所以不能同时有两个CFile打开同一个文件

参见CFile构造函数的nOpenFlags参数的说明：

CFile::shareDenyNone Opens the file without denying other processes read or write access to the file. Create fails if the file has been opened in compatibility mode by any other process.

CFile::shareDenyRead Opens the file and denies other processes read access to the file. Create fails if the file has been opened in compatibility mode or for read access by any other process.

CFile::shareDenyWrite Opens the file and denies other processes write access to the file. Create fails if the file has been opened in compatibility mode or for write access by any other process.

CFile::shareExclusive Opens the file with exclusive mode, denying other processes both read and write access to the file. Construction fails if the file has been opened in any other mode for read or write access, even by the current process.

CFile::shareCompat This flag is not available in 32-bit and 64-bit MFC. This flag maps to CFile::shareExclusive when used in CFile::Open.

[yeyi771]

受用!!