fopen模式 [英] fopen modes
问题描述
r +和w +有真正的区别吗？我在我的手册页中读到r +
打开了一个文件进行读写，而w +打开了一个文件进行阅读和
写作，如果文件不存在的话会被创造出来。如果它存在它
将被截断。
比尔
Is there a real difference in r+ and w+ ? I read in my man pages that r+
opened a file for reading and writing while w+ opened a file for reading and
writing and if the file didn''t exist it would by created. If it existed it
would be truncated.
Bill
推荐答案
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哈希：SHA1
Bill Cunningham写道：
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Bill Cunningham wrote:
r +和w +有真正的区别吗？我在我的手册页中读到r +
打开了一个文件进行读写，而w +打开了一个文件进行阅读和
写作，如果文件不存在的话会被创造出来。如果它存在它将会截断.b $ b将被截断。
Is there a real difference in r+ and w+ ? I read in my man pages that r+
opened a file for reading and writing while w+ opened a file for reading and
writing and if the file didn''t exist it would by created. If it existed it
would be truncated.
这就是区别。 r +不会截断文件，它只是打开它
并允许读写。与w +一起fopen总是返回一个句柄来获得具有读写权限的
空文件。
Pawel Dziepak
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That''s the difference. r+ doesn''t truncate the file, it just opens it
and allows to read and write. fopen with w+ always returns a handle to
empty file with read and write privileges.
Pawel Dziepak
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2008年11月3日15:14，在comp.lang.c中，Bill Cunningham
（no****@nspam.invalid）写道：
On November 3, 2008 15:14, in comp.lang.c, Bill Cunningham
(no****@nspam.invalid) wrote:
r +和w +有真正的区别吗？我在我的手册页中读到了
r +
打开了一个文件进行读写，而w +打开了一个文件供阅读
和写作，如果文件不存在它会被创建。如果它存在
，它将被截断。
Is there a real difference in r+ and w+ ? I read in my man pages that
r+
opened a file for reading and writing while w+ opened a file for reading
and writing and if the file didn''t exist it would by created. If it
existed it would be truncated.
比尔，问问自己这个......
"什么会fopen（" MyFile"，" r +"）如果文件MyFile，则返回/返回没有
存在吗？
现在，问问自己
"什么会fopen（MyFile，" ; w +）如果文件MyFile，则返回/返回。没有
存在吗？
你的两个答案是否相同？如果不是，为什么不呢？
（提示：文档是否说r +会创建文件，如果它是
不存在吗？）
-
Lew Pitcher
Master Code代理& JOAT-in-training |已注册的Linux用户＃112576
http://pitcher.digitalfreehold.ca/ |可根据要求提供GPG公钥
---------- Slackware - 因为我知道我在做什么。 ------
Bill, ask yourself this...
"What would fopen("MyFile","r+") do/return if the file "MyFile" didn''t
exist?
Now, ask yourself
"What would fopen("MyFile","w+") do/return if the file "MyFile" didn''t
exist?
Are your two answers the same? If not, why not?
(Hint: Does the documentation say that "r+" will create the file if it
doesn''t exist?)
--
Lew Pitcher
Master Codewright & JOAT-in-training | Registered Linux User #112576
http://pitcher.digitalfreehold.ca/ | GPG public key available by request
---------- Slackware - Because I know what I''m doing. ------
" Lew Pitcher" < lp ****** @ teksavvy.com写在留言中
新闻：c3 ************************ ** @ TEKSAVVY.COM ......
"Lew Pitcher" <lp******@teksavvy.comwrote in message
news:c3**************************@TEKSAVVY.COM...
（提示：文档是否说r +将创建文件，如果它是
不存在？）
(Hint: Does the documentation say that "r+" will create the file if it
doesn''t exist?)
我对我在posix系统上读到的文档的理解，没有
文件需要已经存在。
比尔
Too my understanding of the docs that I read on my posix system, no the
file needs to already exist.
Bill
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