unsigned char和char指针之间的区别 [英] Difference between unsigned char and char pointers

问题描述

我对 unsigned char （在WinAPI中也是 BYTE ）和 char 指针。

I'm a bit confused with differences between unsigned char (which is also BYTE in WinAPI) and char pointers.

目前我正在使用一些基于ATL的旧代码，的以下表达式：

Currently I'm working with some ATL-based legacy code and I see a lot of expressions like the following:

CAtlArray<BYTE> rawContent;
CALL_THE_FUNCTION_WHICH_FILLS_RAW_CONTENT(rawContent);
return ArrayToUnicodeString(rawContent);
// or return ArrayToAnsiString(rawContent);

现在， ArrayToXXString 的实现

CStringA ArrayToAnsiString(const CAtlArray<BYTE>& array)
{
    CAtlArray<BYTE> copiedArray;
    copiedArray.Copy(array);
    copiedArray.Add('\0');

    // Casting from BYTE* -> LPCSTR (const char*).
    return CStringA((LPCSTR)copiedArray.GetData());
}

CStringW ArrayToUnicodeString(const CAtlArray<BYTE>& array)
{
    CAtlArray<BYTE> copiedArray;
    copiedArray.Copy(array);

    copiedArray.Add('\0');
    copiedArray.Add('\0');

    // Same here.        
    return CStringW((LPCWSTR)copiedArray.GetData());
}

---

< c $ c>到 LPCSTR （ const char * ）可以安全吗？

在将数组数据转换为宽字符串时，是否真的需要添加 double null终止？

Is it really necessary to add double null-termination when converting array data to wide-character string?

转换例程 CStringW（（LPCWSTR）copiedArray.GetData（））似乎对我无效，

The conversion routine CStringW((LPCWSTR)copiedArray.GetData()) seems invalid to me, is that true?

推荐答案

C标准在定义一个字节时是很奇怪的。你确实有几个保证。

The C standard is kind of weird when it comes to the definition of a byte. You do have a couple of guarantees though.

• 字节总是大小为一个字符
  
  
  
  • 返回1
  
  

  这个定义不适用于老的平台，其中一个字节是6或7位长，但它的意思是 BYTE *，和 char * 保证是等价的。

  This definition doesn't mesh well with older platforms where a byte was 6 or 7 bits long, but it does mean BYTE*, and char * are guaranteed to be equivalent.

  在Unicode字符串的末尾需要多个空值，以零（空）字节开头的Unicode字符。

  Multiple nulls are needed at the end of a Unicode string because there are valid Unicode characters that start with a zero (null) byte.

  为了使代码更容易阅读，这完全是一个风格问题。这段代码看起来是用很多旧的C Windows代码使用的样式写的，这已经失去了赞成。可能有很多方法让你更清楚，但如何使它更清晰没有明确的答案。

  As for making the code easier to read, that is completely a matter of style. This code appears to be written in a style used by a lot of old C Windows code, which has definitely fallen out of favor. There are probably a ton of ways to make it clearer for you, but how to make it clearer has no clear answer.

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