是否需要在Delphi中将字符串转换为WideString？ [英] Is it necessary to convert string to WideString in Delphi?

问题描述

我发现一个Windows API函数执行字符串的自然比较。它定义如下：

I found a Windows API function that performs "natural comparison" of strings. It is defined as follows:

int StrCmpLogicalW(
    LPCWSTR psz1,
    LPCWSTR psz2
);

要在Delphi中使用它，我以这种方式宣布：

To use it in Delp I declared it this way:

interface
  function StrCmpLogicalW(psz1, psz2: PWideChar): integer; stdcall;

implementation
  function StrCmpLogicalW; external 'shlwapi.dll' name 'StrCmpLogicalW';

因为它比较了 Unicode 字符串，当我想比较ANSI字符串时，我不知道如何调用它。似乎足以将字符串转发到WideString，然后到FlideChar，但是我不知道这种方法是否正确：

Because it compares Unicode strings, I'm not sure how to call it when I want to compare ANSI strings. It seems to be enough to cast strings to WideString and then to PWideChar, however, I have no idea whether this approach is correct:

function AnsiNaturalCompareText(const S1, S2: string): integer;
begin
  Result := StrCmpLogicalW(PWideChar(WideString(S1)), PWideChar(WideString(S2)));
end;

我对字符编码知之甚少，这是我问题的原因。这个函数是否正常，或者我应该首先将比较的字符串转换为某种方式？

I know very little about character encoding so this is the reason of my question. Is this function OK or should I first convert both the compared strings somehow?

推荐答案

请记住，将一个字符串转换为WideString将使用默认的系统代码页进行转换，这可能或可能不是您需要的。通常情况下，您需要使用当前用户的区域设置。

Keep in mind that casting a string to a WideString will convert it using default system codepage which may or may not be what you need. Typically, you'd want to use current user's locale.

从 System.pas中的WCharFromChar ：

Result := MultiByteToWideChar(DefaultSystemCodePage, 0, CharSource, SrcBytes,
  WCharDest, DestChars);

您可以通过调用 SetMultiByteConversionCodePage 。

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