Strange prototype for memset

[Noob]

Hello,

My documentation for memset states

void *memset(const void *DST, int C, size_t LENGTH);

Strange prototype. That would make memset somewhat not very useful, it seems.

 

[Chris M. Thomasson]

Hello,

My documentation for memset states

void *memset(const void *DST, int C, size_t LENGTH);

Strange prototype. That would make memset somewhat not very useful, it
seems.

Must be a typo.

 

[Keith Thompson]

My documentation for memset states

void *memset(const void *DST, int C, size_t LENGTH);

Strange prototype. That would make memset somewhat not very useful,
it seems.

Where did you see that?

The correct prototype is

void *memset(void *s, int c, size_t n);

 

[bartc]

Hello,

My documentation for memset states

void *memset(const void *DST, int C, size_t LENGTH);

Strange prototype. That would make memset somewhat not very useful,
it seems.

Why not?

 

[Chris M. Thomasson]

Why not?

Well, it would not give a warning for code like:


char const x[] = "Hello";

memset(x, 'X', sizeof(x) - 1);

 

[Richard Tobin]

void *memset(const void *DST, int C, size_t LENGTH);

[/QUOTE]

Must be a typo.

Does "const void *" mean anything? What is the object that it asserts
will not be modified?

-- Richard

 

[bartc]

Doesn't "const void *DST" mean that the function won't change what's
pointed to by DST?

Sounds like a typo in his documentation. What does the actual header file
say?

Maybe the author understood 'const' as well as I do. I would have guessed it
meant the pointer itself (inside memset()) couldn't be assigned to.

 

[Alexander Bartolich]

[...]
Doesn't "const void *DST" mean that the function won't change what's
pointed to by DST?

Sounds like a typo in his documentation. What does the actual header file
say?

Maybe the author understood 'const' as well as I do. I would have guessed it
meant the pointer itself (inside memset()) couldn't be assigned to.

Keyword »const« applies to the thing at its left, unless there is nothing
at its left. So »const void *DST« is equivalent to »void const *DST« and
specifies that the »void« at its left is write-protected.

To write-protect the pointer itself you should specify »void *const DST«.
And of course you can combine the two things: »void const *const DST«.

 

[Richard Bos]

My documentation for memset states

void *memset(const void *DST, int C, size_t LENGTH);

Strange prototype. That would make memset somewhat not very useful, it seems.

Strange, indeed. Documentation from which source?

Richard

 

[Noob]

Strange, indeed. Documentation from which source?

Cygwin.

man memset prints

NEWLIB
2006 Aug 09
MEMSET(3)

 

[Keith Thompson]

Cygwin.

man memset prints

NEWLIB
2006 Aug 09
MEMSET(3)

This is a bug in Cygwin and/or newlib. I've just posted a report on
the Cygwin mailing list:

<http://cygwin.com/ml/cygwin/2009-08/msg00748.html>

Note that the error is only in the man page; the actual declaration of
memset doesn't have the "const".

 

[Noob]

This is a bug in Cygwin and/or newlib. I've just posted a report on
the Cygwin mailing list:

<http://cygwin.com/ml/cygwin/2009-08/msg00748.html>

Thanks for taking the time to file a bug report

 

[Keith Thompson]

This is a bug in Cygwin and/or newlib. I've just posted a report on
the Cygwin mailing list:

<http://cygwin.com/ml/cygwin/2009-08/msg00748.html>

Note that the error is only in the man page; the actual declaration of
memset doesn't have the "const".

Response from Eric Blake at
<http://cygwin.com/ml/cygwin/2009-08/msg00754.html>:

| Indeed. However, this was already fixed in newlib on 2008-05-27, so it
| will be corrected the next time someone rebuilds the man pages.