'const char'和'char'之间的区别 [英] Differences between 'const char' and 'char'

问题描述

这两个陈述有什么区别？是否有任何主要的

差异？


const char filename [] =" ips_c.txt";

char filename [ ] =" ips_c.txt";


谢谢!!!

解决方案

hokieghal99< ho ******** @ hotmail.com>写在

新闻：bl ********* @ solaris.cc.vt.edu：

这两者有什么区别声明？是否有任何重大差异？

const char filename [] =" ips_c.txt" ;;
char filename [] =" ips_c.txt";

只有编译时差。如果你试图写入文件名的第一个

定义，就像在文件名[0] =''我'中那样，你将得到一个

编译时错误。为第二个定义做同样的事情，你

将没有错误，文件名[]将包含Ips_c.txt。


off-topic ：有些实现可能会将const版本放入某种类型的只读内存中。


-

- Mark - >

-

hokieghal99< ho ******** @ hotmail.com>写道：

这两个陈述有什么区别？是否有任何重大差异？

const char filename [] =" ips_c.txt" ;;
char filename [] =" ips_c.txt";

首先，这些是声明，而不是声明[*]。第二，是的，

存在差异：尝试修改前文件名'

会产生未定义的行为。允许C实现

将前文件名置于只读状态。内存部分。

[*]在C99中，声明可以是声明，但它仍然是误导的b $ b。

- -

"这将是未定义行为的一个更好的例子

如果行为未定义。

- 迈克尔鲁宾斯坦

" Mark A. Odell" <无**** @ embeddedfw.com>写道：

hokieghal99< ho ******** @ hotmail.com>在
新闻中写道：bl ********* @ solaris.cc.vt.edu：

这两个陈述有什么区别？是否有任何重大的差异？

const char filename [] =" ips_c.txt";
char filename [] =" ips_c.txt";
只有编译时差。如果您尝试写入文件名的第一个
定义，如filename [0] =''我'，您将收到编译时错误。为第二个定义做同样的事情，你将没有错误，文件名[]将包含Ips_c.txt。

它可能是与你的C

实现只有编译时差异，但标准没有说明这一点。

偏离主题：某些实现可能会放置const版本在某种情况下只读内存。

因此，可能存在运行时差异。

-

事实上，有一场圣战并不意味着其中一方

并不吸吮 - 通常两者都做...... />
- 亚历山大·维罗

What is the difference between these two statements? Are there any major
differences?

const char filename[] = "ips_c.txt";
char filename[] = "ips_c.txt";

Thanks!!!

解决方案

hokieghal99 <ho********@hotmail.com> wrote in
news:bl*********@solaris.cc.vt.edu:

What is the difference between these two statements? Are there any major
differences?

const char filename[] = "ips_c.txt";
char filename[] = "ips_c.txt";

Only a compile time difference. If you attempt to write to the first
definition of filename, as in filename[0] = ''I'' you will get a
compile-time error. Do the same thing for the second definition and you
will get no error and filename[] will contain "Ips_c.txt".

off-topic: some implementations may place the const version into some sort
of read-only memory.

--
- Mark ->
--

hokieghal99 <ho********@hotmail.com> writes:

What is the difference between these two statements? Are there any
major differences?

const char filename[] = "ips_c.txt";
char filename[] = "ips_c.txt";

First, these are declarations, not statements[*]. Second, yes,
there is a difference: attempting to modify the former `filename''
yields undefined behavior. The C implementation is allowed to
place the former `filename'' in a "read-only" section of memory.
[*] In C99, a declaration can be a statement, but it''s still
misleading.
--
"It would be a much better example of undefined behavior
if the behavior were undefined."
--Michael Rubenstein

"Mark A. Odell" <no****@embeddedfw.com> writes:

hokieghal99 <ho********@hotmail.com> wrote in
news:bl*********@solaris.cc.vt.edu:

What is the difference between these two statements? Are there any major
differences?

const char filename[] = "ips_c.txt";
char filename[] = "ips_c.txt";
Only a compile time difference. If you attempt to write to the first
definition of filename, as in filename[0] = ''I'' you will get a
compile-time error. Do the same thing for the second definition and you
will get no error and filename[] will contain "Ips_c.txt".

It may be only a compile-time difference with your C
implementation, but the standard doesn''t say anything about that.
off-topic: some implementations may place the const version into some sort
of read-only memory.

Thus, there may be a runtime difference.
--
"The fact that there is a holy war doesn''t mean that one of the sides
doesn''t suck - usually both do..."
--Alexander Viro

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