NULL指针内部表示。 [英] NULL pointer internal representation.
问题描述
我读到指针表示可以非零位模式，机器
specific.Compiler当值为'0'时在指针上下文中，
将其转换为机器特定的空指针位模式。
我的问题是程序是否引用了特定值
机器用来引用空指针，编译器如何对待
那个？。
谢谢，
-Khan
Hi,
I read that pointer representation can non-zero bit pattern, machine
specific.Compiler when comes accross value ''0'' in pointer context,
converts it to machine specific null pointer bit-pattern.
My question is if a program refers to that specific value which is
used by the machine to refer to null pointer, how compiler treats
that?.
Thanks,
-Khan
推荐答案
khan写道：
khan wrote:
我读过指针表示可以非零位模式，机器
specific.Compiler在指针上下文中有值''0'时，
将它转换为机器特定的空指针位模式。
I read that pointer representation can non-zero bit pattern, machine
specific.Compiler when comes accross value ''0'' in pointer context,
converts it to machine specific null pointer bit-pattern.
是的：空指针的内部表示是
C实现发现方便的，编译器替换了
null指针常量（指针上下文中的文字零值），
方便的值。
Yes: the internal representation of the null pointer is whatever the
C implementation finds convenient, with the compiler replacing the
null pointer constant (a literal zero value in pointer context) with
its convenient value.
我的问题是程序指的是机器用来引用空指针的那个特定值，这是编译器如何处理
那个？
My question is if a program refers to that specific value which is
used by the machine to refer to null pointer, how compiler treats
that?
（fx：rhetorical）如果
保持在标准范围内，该计划将如何实现这一目标？
[不可能，所以编译器不需要对它做任何事情。]
-
"生活充满了神秘感。考虑其中一个。 Sinclair，/ Babylon 5 /
Hewlett-Packard Limited注册办事处：Cain Road，Bracknell，
注册号：690597 England Berks RG12 1HN
(fx:rhetorical) How would the program manage to do that while
staying inside the Standard?
[It can''t, so the compiler doesn''t need to do anything about it.]
--
"Life is full of mysteries. Consider this one of them." Sinclair, /Babylon 5/
Hewlett-Packard Limited registered office: Cain Road, Bracknell,
registered no: 690597 England Berks RG12 1HN
4月27日下午3:59，Chris Dollin< chris.dol ... @ hp.comwrote：
On Apr 27, 3:59 pm, Chris Dollin <chris.dol...@hp.comwrote:
khan写道：
khan wrote:
我读到指针表示可以非零位模式，机器
specific.Compiler什么时候来指针上下文中的值0，
将其转换为机器特定的空指针位模式。
I read that pointer representation can non-zero bit pattern, machine
specific.Compiler when comes accross value ''0'' in pointer context,
converts it to machine specific null pointer bit-pattern.
是的：空指针的内部表示是
C实现发现方便的，编译器替换了
null指针常量（指针上下文中的文字零值），
方便的值。
Yes: the internal representation of the null pointer is whatever the
C implementation finds convenient, with the compiler replacing the
null pointer constant (a literal zero value in pointer context) with
its convenient value.
我的问题是程序指的是机器用来引用空指针的那个特定值，这是编译器如何处理
那个？
My question is if a program refers to that specific value which is
used by the machine to refer to null pointer, how compiler treats
that?
（fx：rhetorical）如果
留在标准内，该计划将如何实现这一目标？
[不可能，所以编译器不需要对它做任何事情。]
-
"生活充满了神秘感。考虑其中一个。 Sinclair，/ Babylon 5 /
Hewlett-Packard Limited注册办事处：Cain Road，Bracknell，
注册号：690597 England Berks RG12 1HN
(fx:rhetorical) How would the program manage to do that while
staying inside the Standard?
[It can''t, so the compiler doesn''t need to do anything about it.]
--
"Life is full of mysteries. Consider this one of them." Sinclair, /Babylon 5/
Hewlett-Packard Limited registered office: Cain Road, Bracknell,
registered no: 690597 England Berks RG12 1HN
我想确认一下我对这些的理解：
一个教程将表示空指针指向某些
特定值，它不在处理器的地址空间中，并且
哪个处理器视为无指针的空指针。
谢谢，
-Mushtaq
I want to confirm my understanding on these:
A proessor will have the representation of null pointer to some
specific value, which is not in the address space of the processor and
which processor treats as a null pointer that points nowhere.
Thanks,
-Mushtaq
khan< mu ********* @ gmail.comwrote：
khan <mu*********@gmail.comwrote:
4月27日下午3:59，Chris Dollin< chris.dol ... @ hp.comwrote：
On Apr 27, 3:59 pm, Chris Dollin <chris.dol...@hp.comwrote:
khan写道：
khan wrote:
我读到指针表示可以非零位模式，机器
specific.Compiler when来自va lue''0''在指针上下文中，
将其转换为机器特定的空指针位模式。
I read that pointer representation can non-zero bit pattern, machine
specific.Compiler when comes accross value ''0'' in pointer context,
converts it to machine specific null pointer bit-pattern.
是的：空指针的内部表示是
C实现发现方便的，编译器替换了
null指针常量（指针上下文中的文字零值），
方便的值。
Yes: the internal representation of the null pointer is whatever the
C implementation finds convenient, with the compiler replacing the
null pointer constant (a literal zero value in pointer context) with
its convenient value.
我的问题是程序指的是机器用来引用空指针的那个特定值，这是编译器如何处理
那个？
My question is if a program refers to that specific value which is
used by the machine to refer to null pointer, how compiler treats
that?
（fx：rhetorical）如果
保持在标准范围内，该计划将如何实现这一目标？
[不可能，所以编译器不需要对它做任何事情。]
(fx:rhetorical) How would the program manage to do that while
staying inside the Standard?
[It can''t, so the compiler doesn''t need to do anything about it.]
我想确认一下我对这些的理解：
一个过程会有一个空指针表示某些
特定值，
I want to confirm my understanding on these:
A proessor will have the representation of null pointer to some
specific value,
是;
Yes;
不在处理器的地址空间中且
which is not in the address space of the processor and
不，但实际上与其他点无关（虽然我不知道
任何处理器如何引用不在其自己地址的指针
空间）;
no, but actually not relevant to the other points (although I wonder how
any processor could refer to a pointer which is not in its own address
space);
哪个处理器将其视为无指针的空指针。
which processor treats as a null pointer that points nowhere.
和是。
Richard
and yes.
Richard
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