如何处理来自“const char *”的翻译to“const unsigned char *”？ [英] how to deal with the translation from "const char * " to "const unsigned char *"?

问题描述

我写道：

------------------------------------ -----------------------------------

------- ---------------------------------

unsigned char * p = reinterpret_cast< unsigned char *>（" abcdg"）;

sizeof（reinterpret_cast< const char *>（p））;

---------- -------------------------------------------------- -----------

------------------------------- ---------


编译器告诉我reinterpret_cast from typeconst char *"

to type" unsigned char *抛弃constness"

解决方案

1月28日晚上11:21 ，？1 ?? 1 ??¤§？¤???? < chendong ... @ gmail.comwrote：

i写道：--------------------- --------------------------------------------------

----------------------------------------

unsigned char * p = reinterpret_cast< unsigned char *>（" abcdg"）;

sizeof（reinterpret_cast< const char *>（p））;

--------------------------------------------- --------------------------

---------------- ------------------------


编译器告诉我reinterpret_cast from typeconst char *

键入unsigned char *抛弃了constness

此时你停止与C ++废话摔跤，只需使用

C风格的演员。


好​​的旧C风格演员将隐式生成reinterpret_cast和static_cast的正确

组合，而没有措辞

使你的代码混乱。


由于没有涉及其含义可能会改变的typedef名称，因此C

样式的演员阵容不比新的演员组合更安全，并且是

更具可读性。


（如果你使用抽象类型的C演员，比如把一些A *演绎到一些B *，那么就有危险就是有人可能会重新定义A和B是什么，并且演员将默默地继续工作，即使改变可能是b $ b，这样转换会产生错误的后果）。 />

？1【1】¤§？¤????写道：

i写道：

---------------------- -------------------------------------------------

----------------------------------------

unsigned char * p = reinterpret_cast< unsigned char *>（" abcdg"）;

sizeof（reinterpret_cast< const char *>（p））;

---------------------------------------------- -------------------------

----------------- -----------------------


编译器告诉我reinterpret_cast from typeconst char *

键入unsigned char *抛弃constness"

编译器是对的。 unsigned char *是非常量和字符串

文字（如abcdg）是常量。

如果你要转换为unsigned char *你需要问问自己为什么。

演员之后会修改吗？ （这将是未定义和吐司

您在某些平台上的过程）


看起来您有设计问题。

?????写道：

i写道：

---------------------- -------------------------------------------------

----------------------------------------

unsigned char * p = reinterpret_cast< unsigned char *>（" abcdg"）;

sizeof（reinterpret_cast< const char *>（p））;

---------------------------------------------- -------------------------

----------------- -----------------------


编译器告诉我reinterpret_cast from typeconst char *

键入unsigned char *抛弃了constness

在您发布的代码中，您不会转换为const unsigned char *。尝试：


unsigned char const * p = static_cast< unsigned char const *>（" abcdg"）;

Best


Kai-Uwe Bux

i wrote:
-----------------------------------------------------------------------
----------------------------------------
unsigned char * p = reinterpret_cast<unsigned char *>("abcdg");
sizeof(reinterpret_cast<const char *>(p));
-----------------------------------------------------------------------
----------------------------------------

the compiler tells me that "reinterpret_cast from type "const char * "
to type "unsigned char *" casts away constness "

解决方案

On Jan 28, 11:21 pm, "?1??1??¤§?¤????" <[e-mail]:

i wrote:-----------------------------------------------------------------------
----------------------------------------
unsigned char * p = reinterpret_cast<unsigned char *>("abcdg");
sizeof(reinterpret_cast<const char *>(p));
-----------------------------------------------------------------------
----------------------------------------

the compiler tells me that "reinterpret_cast from type "const char * "
to type "unsigned char *" casts away constness "

At this point you stop wrestling with the C++ bullshit and just use a
C style cast.

The good old C style cast will implicitly produce the correct
combination of reinterpret_cast and static_cast, without the verbiage
cluttering your code.

Since no typedef names are involved whose meanings could change, the C
style cast is no less safe than the new style cast combination, and is
much more readable.

(If you use the C cast with abstracted types, like casting some A * to
some B *, the danger is that someone may redefine what A and B is, and
the cast will silently continue to work, even though the change may be
such that the conversion has erroneous consequences).

?1??1??¤§?¤???? wrote:

i wrote:
-----------------------------------------------------------------------
----------------------------------------
unsigned char * p = reinterpret_cast<unsigned char *>("abcdg");
sizeof(reinterpret_cast<const char *>(p));
-----------------------------------------------------------------------
----------------------------------------

the compiler tells me that "reinterpret_cast from type "const char * "
to type "unsigned char *" casts away constness "

The compiler is right. "unsigned char *" is non-const and string
literals (like "abcdg") are const.
If you''re casting to a "unsigned char *" you need to ask yourself why.
Will it be modified after the cast ? (that would be undefined and toast
your process on some platforms)

It seems like you have a design problem.

????? wrote:

i wrote:
-----------------------------------------------------------------------
----------------------------------------
unsigned char * p = reinterpret_cast<unsigned char *>("abcdg");
sizeof(reinterpret_cast<const char *>(p));
-----------------------------------------------------------------------
----------------------------------------

the compiler tells me that "reinterpret_cast from type "const char * "
to type "unsigned char *" casts away constness "

In the code you posted, you do not cast to "const unsigned char *". Try:

unsigned char const * p = static_cast<unsigned char const *>("abcdg");
Best

Kai-Uwe Bux

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