On 2020-01-17 15:34, Paul Procacci wrote:
Todd (and others),
So a few things.
1)
JJ's example worked by chance. (sorry JJ).
It worked because it just so happens that either his OS zero filled the
block he was allocated by the allocator
or because he didn't reuse the block that was given to him initially by
the allocator.
2)
If you assume that the function set_foo($array) expects a NULL
terminated string, only then is the documentation a problem.
However, there's not enough information in the C prototype to make this
assumption. There's also no set_foo($array) function body to explore.
# C prototype is void set_foo(const char *)
All this says is that the subroutine is receiving a pointer to memory
containing bytes and nothing more.
The body of the function _may_ simply check the first 3 bytes. This is
up to the reader to ascertain.
3) As for a documentation update, I'm unsure if it's required. The
example is not only perfectly valid raku, it's also perfectly valid C.
Actually, it is not perfectly okay with C. Let me state
my case:
Take a peak at N1570, 5.2.1p2, 7.1.1 and 6.7.9,p14.
leaving off the nul is not a valid way of presenting a
string to a C function.
C can not figure out where the end of the string is
on its own without the nul. It will careen until it
find a nul. Even further if the string is UTF16 and
is looking for a double nul (0x0000);
Now if you want to do a "String Literal", you can
leave the nul off. But it required that you inform
to other end as to the String Literal's length. And
a "String Literal" IS NOT a C string.
"String Literal's" are covered by N1570 6.7.9,p14
An example of a string literal can be found at:
https://docs.microsoft.com/en-us/windows/win32/api/winreg/nf-winreg-regsetvalueexw
"const BYTE *lpData" points to the String Leteral, and
"DWORD cbData" contains the length of the string literal
C Strings and String Literals are two vastly different things.
In that same example:
"LPCWSTR lpValueName" points to a C String that must
be nul terminated. Note that there is no companion
variable stating its length
Perhaps something could be added to remove whatever ambiguity you
perceive, but you argument stems from something that isn't necessarily
true in this example
and that's the function set_foo($array) expects a NULL terminated string.
~Paul
Hi Paul,
This is the example I previously posted of careening
that drove me crazy trying to troubleshoot. The C guys
told me it was not a convincing example.
https://ibb.co/tHy7ZQM
The C Spec N1570, 5.2.1, p2 is very clear:
A byte with
all bits set to 0, called the
null character, shall exist in the basic
execution character set; it
is used to
terminate a character string.
And not including it causes all kinds of consternation,
as I found out the hard way.
-T
