在Delphi 2010中写一个字符串到TFileStream [英] Writing a string to a TFileStream in Delphi 2010

问题描述

我有Delphi 2007代码如下：

  procedure WriteString（Stream：TFileStream; var SourceBuffer：PChar; s ：string）; 
 begin 
 StrPCopy（SourceBuffer，s）; 
 Stream.Write（SourceBuffer [0]，StrLen（SourceBuffer））; 
结束
  

我称之为：

  var 
 SourceBuffer：PChar; 
 MyFile：TFileStream; 
 
 .... 
 
 SourceBuffer：= StrAlloc（1024）; 
 MyFile：= TFileStream.Create（'MyFile.txt'，fmCreate）; 
 WriteString（MyFile，SourceBuffer，'Some Text'）; 
 .... 
  

这在Delphi 2007中有效，但它给了我很多Delphi 2010中的垃圾字符。我知道这是由于unicode合规性问题，但我不知道如何解决这个问题。

这是我试过的far：

• 更改
  SourceBuffer的数据类型（以及WideString预期的参数
  ）到PWideChar




• 列出的每个建议
  这里

我做错了什么？

解决方案

您不需要单独的缓冲区来将字符串写入流。可能最简单的方法是将字符串编码为UTF8，如下所示：

  procedure TStreamEx.writeString（const data：串）; 
 var 
 len：cardinal; 
 oString：UTF8String; 
 begin 
 oString：= UTF8String（data）; 
 len：= length（oString）; 
 self.WriteBuffer（len，4）; 
如果len> 0然后
 self.WriteBuffer（oString [1]，len）; 
结束
 
函数TStreamEx.readString：string; 
 var 
 len：integer; 
 iString：UTF8String; 
 begin 
 self.readBuffer（len，4）; 
如果len> 0然后
 begin 
 setLength（iString，len）; 
 self.ReadBuffer（iString [1]，len）; 
 result：= string（iString）; 
结束
结束
  

我已经将TStreamEx声明为TStream的类帮助器，但不应该太难将这些重写为独立程序和函数，就像您的示例。

I have Delphi 2007 code that looks like this:

procedure WriteString(Stream: TFileStream; var SourceBuffer: PChar; s: string);
begin
  StrPCopy(SourceBuffer,s);
  Stream.Write(SourceBuffer[0], StrLen(SourceBuffer));
end;

I call it like this:

var
  SourceBuffer : PChar;
  MyFile: TFileStream;

....

SourceBuffer := StrAlloc(1024);
MyFile := TFileStream.Create('MyFile.txt',fmCreate);
WriteString(MyFile,SourceBuffer,'Some Text');
....

This worked in Delphi 2007, but it gives me a lot of junk characters in Delphi 2010. I know this is due to unicode compliance issues, but I am not sure how to address the issue.

Here is what I've tried so far:

• Change the data type of SourceBuffer(and also the parameter expected by WideString) to PWideChar

• Every one of the suggestions listed here

What am I doing wrong?

解决方案

You don't need a separate buffer to write a string to a stream. Probably the simplest way to do it is to encode the string to UTF8, like so:

procedure TStreamEx.writeString(const data: string);
var
   len: cardinal;
   oString: UTF8String;
begin
   oString := UTF8String(data);
   len := length(oString);
   self.WriteBuffer(len, 4);
   if len > 0 then
      self.WriteBuffer(oString[1], len);
end;

function TStreamEx.readString: string;
var
   len: integer;
   iString: UTF8String;
begin
   self.readBuffer(len, 4);
   if len > 0 then
   begin
      setLength(iString, len);
      self.ReadBuffer(iString[1], len);
      result := string(iString);
   end;
end;

I've declared TStreamEx as a class helper for TStream, but it shouldn't be too difficult to rewrite these as a solo procedure and function like your example.

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