blocks|key|5309392|text|试试彼得·莫里斯的FastStrings.pas吧。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|5309393|entityMap|0|LINK|mutability|MUTABLE|url|http://www.koders.com/delphi/fidFB386C5C240FD5E72013C882ADD7600FDF60E6C7.aspx?s=socket^0|9|F|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

Try <a href="http://www.koders.com/delphi/fidFB386C5C240FD5E72013C882ADD7600FDF60E6C7.aspx?s=socket" rel="noreferrer">FastStrings.pas</a> from Peter Morris.

blocks|key|3053873|text|如果你使用的是Delphi2009，这个操作在TStringBuilder中比在ReplaceString中快3倍。它也是Unicode安全的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3053874|我使用http://www.CodeGear.com中的文本，并将所有出现的"<“和">”更改为"&lt;"和"&gt;"作为起点。|offset|length|style|CODE|3053875|包括字符串赋值和创建/释放对象，在我的系统上分别花费了大约25ms和75ms：|3053876|function+TForm1.TestStringBuilder(const+aString:+string):+string;
var
++sb:+TStringBuilder;
begin
++StartTimer;
++sb+:=+TStringBuilder.Create;
++sb.Append(aString);
++sb.Replace('&gt;',+'>');
++sb.Replace('&lt;',+'<');
++Result+:=+sb.ToString();
++FreeAndNil(sb);
++StopTimer;
end;

function+TForm1.TestStringReplace(const+aString:+string):+string;
begin
++StartTimer;
++Result+:=+StringReplace(aString,'&gt;','>',[rfReplaceAll])+;
++Result+:=+StringReplace(Result,'&lt;','<',[rfReplaceAll])+;
++StopTimer;
end;|code-block|syntax|javascript|3053877|entityMap|0|LINK|mutability|MUTABLE|url|http://www.codegear.com/^0|0|1C|6|1J|6|3|N|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|X|8|@$D|Y|E|Z|F|G]|$D|10|E|11|F|G]]|9|@$D|12|E|13|1|14]]|A|$]]|$1|H|3|I|5|6|7|15|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|16|8|@]|9|@]|A|$M|N]]|$1|O|3|-4|5|6|7|17|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|V]]]]

If you're using Delphi 2009, this operation is about 3 times faster with TStringBuilder than with ReplaceString. It's Unicode safe, too.

I used the text from <a href="http://www.CodeGear.com" rel="nofollow noreferrer">http://www.CodeGear.com</a> with all occurrences of "&lt;" and ">" changed to <code>"&amp;lt;"</code> and <code>"&amp;gt;"</code> as my starting point.

Including string assignments and creating/freeing objects, these took about 25ms and 75ms respectively on my system:

<pre><code>function TForm1.TestStringBuilder(const aString: string): string;
var
 sb: TStringBuilder;
begin
 StartTimer;
 sb := TStringBuilder.Create;
 sb.Append(aString);
 sb.Replace('&amp;gt;', '&gt;');
 sb.Replace('&amp;lt;', '&lt;');
 Result := sb.ToString();
 FreeAndNil(sb);
 StopTimer;
end;

function TForm1.TestStringReplace(const aString: string): string;
begin
 StartTimer;
 Result := StringReplace(aString,'&amp;gt;','&gt;',[rfReplaceAll]) ;
 Result := StringReplace(Result,'&amp;lt;','&lt;',[rfReplaceAll]) ;
 StopTimer;
end;
</code></pre>

blocks|key|3053945|text|您一定要看看快速代码项目页面：http://fastcode.sourceforge.net/|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3053946|他们运行了一个更快的StringReplace+(Ansi+StringReplace挑战赛)的挑战赛，“赢家”比Delphi+RTL快14倍。|3053947|在最近的版本中，Delphi本身已经包含了几个快速代码函数(我认为是在D2007上)，因此性能的提高可能会根据您使用的Delphi版本的不同而显著不同。|3053948|如前所述，如果您真的想处理XML，那么您真的应该考虑基于Unicode的解决方案。|3053949|entityMap|0|LINK|mutability|MUTABLE|url|http://fastcode.sourceforge.net/^0|F|W|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@$A|S|B|T|1|U]]|C|$]]|$1|D|3|E|5|6|7|V|8|@]|9|@]|C|$]]|$1|F|3|G|5|6|7|W|8|@]|9|@]|C|$]]|$1|H|3|I|5|6|7|X|8|@]|9|@]|C|$]]|$1|J|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]]|K|$L|$5|M|N|O|C|$P|Q]]]]

You should definitely look at the Fastcode project pages: <a href="http://fastcode.sourceforge.net/" rel="noreferrer">http://fastcode.sourceforge.net/</a>

They ran a challenge for a faster StringReplace (Ansi StringReplace challenge), and the 'winner' was 14 times faster than the Delphi RTL.

Several of the fastcode functions have been included within Delphi itself in recent versions (D2007 on, I think), so the performance improvement may vary dramatically depending on which Delphi version you are using.

As mentioned before, you should really be looking at a Unicode-based solution if you're serious about processing XML.

blocks|key|3898568|text|问题是您将整个字符串大小迭代了两次(一次用于将>替换为>，另一次用于将<替换为<)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3898569|您应该使用for迭代，并在找到gt；或lt；的&时进行提前检查，然后立即替换，然后跳过3个字符((g%7Cl)t;)。这样，它可以在与字符串xml.Text的大小成比例的时间内做到这一点。|offset|length|style|BOLD|3898570|3898571|这是一个简单的C#示例，因为我不知道Delphi，但应该可以让你大致了解一下。|3898572|String+s+=+"&lt;xml&gt;test&lt;/xml&gt;";
char[]+input+=+s.ToCharArray();
char[]+res+=+new+char[s.Length];
int+j+=+0;
for+(int+i+=+0,+count+=+input.Length;+i+<+count;+%2B%2Bi)
{
++++if+(input[i]+==+'&')
++++{
++++++++if+(i+<+count+-+3)
++++++++{
++++++++++++if+(input[i+%2B+1]+==+'l'+%7C%7C+input[i+%2B+1]+==+'g')
++++++++++++{
++++++++++++++++if+(input[i+%2B+2]+==+'t'+&&+input[i+%2B+3]+==+';')
++++++++++++++++{
++++++++++++++++++++res[j%2B%2B]+=+input[i+%2B+1]+==+'l'+?+'<'+:+'>';
++++++++++++++++++++i+%2B=+3;
++++++++++++++++++++continue;
++++++++++++++++}
++++++++++++}
++++++++}
++++}

++++res[j%2B%2B]+=+input[i];
}
Console.WriteLine(new+string(res,+0,+j));|code-block|syntax|javascript|3898573|这将输出以下内容：|3898574|<xml>test</xml>|3898575|entityMap^0|0|1W|8|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|V|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|W|8|@$D|X|E|Y|F|G]]|9|@]|A|$]]|$1|H|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|10|8|@]|9|@]|A|$]]|$1|K|3|L|5|M|7|11|8|@]|9|@]|A|$N|O]]|$1|P|3|Q|5|6|7|12|8|@]|9|@]|A|$]]|$1|R|3|S|5|M|7|13|8|@]|9|@]|A|$N|O]]|$1|T|3|-4|5|6|7|14|8|@]|9|@]|A|$]]]|U|$]]

The problem is that you are iterating the entire string size twice (one for replacing &amp;gt; by > and another one to replace &amp;lt; by &lt;).

You should iterate with a for and simply check ahead whenever you find a &amp; for a gt; or lt; and do the immediate replace and then skipping 3 characters ((g|l)t;). This way it can do that in proportional time to the size of the string xml.Text.

<hr>

A simple C# example as I do not know Delphi but should do for you to get the general idea.

<pre><code>String s = "&amp;lt;xml&amp;gt;test&amp;lt;/xml&amp;gt;";
char[] input = s.ToCharArray();
char[] res = new char[s.Length];
int j = 0;
for (int i = 0, count = input.Length; i &lt; count; ++i)
{
 if (input[i] == '&amp;')
 {
 if (i &lt; count - 3)
 {
 if (input[i + 1] == 'l' || input[i + 1] == 'g')
 {
 if (input[i + 2] == 't' &amp;&amp; input[i + 3] == ';')
 {
 res[j++] = input[i + 1] == 'l' ? '&lt;' : '&gt;';
 i += 3;
 continue;
 }
 }
 }
 }

 res[j++] = input[i];
}
Console.WriteLine(new string(res, 0, j));
</code></pre>

This outputs:

<pre><code>&lt;xml&gt;test&lt;/xml&gt;
</code></pre>

blocks|key|5309673|text|当您处理多行文本文件时，您可以通过逐行处理它来获得一些性能。此方法将替换大于1MB的xml文件的时间缩短了约90%25。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5309674|procedure+ReplaceMultilineString(xml:+TStrings);
var
++i:+Integer;
++line:+String;
begin
++for+i:=0+to+xml.Count-1+do
++begin
++++line+:=+xml[i];
++++line+:=+StringReplace(line,+'&gt;',+'>',+[rfReplaceAll]);
++++line+:=+StringReplace(line,+'&lt;',+'<',+[rfReplaceAll]);
++++xml[i]+:=+line;
++end;
end;|code-block|syntax|javascript|5309675|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

When you are dealing with a multiline text files, you can get some performance by processing it line by line. This approach reduced time in about 90% to replaces on >1MB xml file.

<pre><code>procedure ReplaceMultilineString(xml: TStrings);
var
 i: Integer;
 line: String;
begin
 for i:=0 to xml.Count-1 do
 begin
 line := xml[i];
 line := StringReplace(line, '&amp;gt;', '&gt;', [rfReplaceAll]);
 line := StringReplace(line, '&amp;lt;', '&lt;', [rfReplaceAll]);
 xml[i] := line;
 end;
end;
</code></pre>

blocks|key|3898623|text|由Jorge+Ferreira编写的未经测试的C#代码转换。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3898624|function+ReplaceLtGt(const+s:+string):+string;
var
++inPtr,+outPtr:+integer;
begin
++SetLength(Result,+Length(s));
++inPtr+:=+1;
++outPtr+:=+1;
++while+inPtr+<=+Length(s)+do+begin
++++if+(s[inPtr]+=+'&')+and+((inPtr+%2B+3)+<=+Length(s))+and
+++++++(s[inPtr%2B1]+in+['l',+'g'])+and+(s[inPtr%2B2]+=+'t')+and
+++++++(s[inPtr%2B3]+=+';')+then
++++begin
++++++if+s[inPtr%2B1]+=+'l'+then
++++++++Result[outPtr]+:=++'<'
++++++else
++++++++Result[outPtr]+:=+'>';
++++++Inc(inPtr,+3);
++++end
++++else+begin
++++++Result[outPtr]+:=+Result[inPtr];
++++++Inc(inPtr);
++++end;
++++Inc(outPtr);
++end;
++SetLength(Result,+outPtr+-+1);
end;|code-block|syntax|javascript|3898625|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Untested conversion of the C# code written by Jorge Ferreira.

<pre><code>function ReplaceLtGt(const s: string): string;
var
 inPtr, outPtr: integer;
begin
 SetLength(Result, Length(s));
 inPtr := 1;
 outPtr := 1;
 while inPtr &lt;= Length(s) do begin
 if (s[inPtr] = '&amp;') and ((inPtr + 3) &lt;= Length(s)) and
 (s[inPtr+1] in ['l', 'g']) and (s[inPtr+2] = 't') and
 (s[inPtr+3] = ';') then
 begin
 if s[inPtr+1] = 'l' then
 Result[outPtr] := '&lt;'
 else
 Result[outPtr] := '&gt;';
 Inc(inPtr, 3);
 end
 else begin
 Result[outPtr] := Result[inPtr];
 Inc(inPtr);
 end;
 Inc(outPtr);
 end;
 SetLength(Result, outPtr - 1);
end;
</code></pre>

blocks|key|3898684|text|Systools+(Turbopower，now+open+source)有一个ReplaceStringAllL函数，可以在一个字符串中完成所有这些操作。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3898685|entityMap|0|LINK|mutability|MUTABLE|url|https://sourceforge.net/projects/tpsystools/^0|L|F|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

Systools (Turbopower, <a href="https://sourceforge.net/projects/tpsystools/" rel="nofollow noreferrer">now open source</a>) has a ReplaceStringAllL function that does all of them in a string.

blocks|key|5309711|text|它像魅力一样工作，所以快点相信它|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5309712|++++Function+NewStringReplace(const+S,+OldPattern,+NewPattern:+string;++Flags:+TReplaceFlags):+string;
var
++OldPat,Srch:+string;+//+Srch+and+Oldp+can+contain+uppercase+versions+of+S,OldPattern
++PatLength,NewPatLength,P,i,PatCount,PrevP:+Integer;
++c,d:+pchar;
begin
++PatLength:=Length(OldPattern);
++if+PatLength=0+then+begin
++++Result:=S;
++++exit;
++end;

++if+rfIgnoreCase+in+Flags+then+begin
++++Srch:=AnsiUpperCase(S);
++++OldPat:=AnsiUpperCase(OldPattern);
++end+else+begin
++++Srch:=S;
++++OldPat:=OldPattern;
++end;

++PatLength:=Length(OldPat);
++if+Length(NewPattern)=PatLength+then+begin
++++//Result+length+will+not+change
++++Result:=S;
++++P:=1;
++++repeat
++++++P:=PosEx(OldPat,Srch,P);
++++++if+P>0+then+begin
++++++++for+i:=1+to+PatLength+do
++++++++++Result[P%2Bi-1]:=NewPattern[i];
++++++++if+not+(rfReplaceAll+in+Flags)+then+exit;
++++++++inc(P,PatLength);
++++++end;
++++until+p=0;
++end+else+begin
++++//Different+pattern+length+->+Result+length+will+change
++++//To+avoid+creating+a+lot+of+temporary+strings,+we+count+how+many
++++//replacements+we're+going+to+make.
++++P:=1;+PatCount:=0;
++++repeat
++++++P:=PosEx(OldPat,Srch,P);
++++++if+P>0+then+begin
++++++++inc(P,PatLength);
++++++++inc(PatCount);
++++++++if+not+(rfReplaceAll+in+Flags)+then+break;
++++++end;
++++until+p=0;
++++if+PatCount=0+then+begin
++++++Result:=S;
++++++exit;
++++end;
++++NewPatLength:=Length(NewPattern);
++++SetLength(Result,Length(S)%2BPatCount*(NewPatLength-PatLength));
++++P:=1;+PrevP:=0;
++++c:=pchar(Result);+d:=pchar(S);
++++repeat
++++++P:=PosEx(OldPat,Srch,P);
++++++if+P>0+then+begin
++++++++for+i:=PrevP%2B1+to+P-1+do+begin
++++++++++c%5E:=d%5E;
++++++++++inc(c);+inc(d);
++++++++end;
++++++++for+i:=1+to+NewPatLength+do+begin
++++++++++c%5E:=NewPattern[i];
++++++++++inc(c);
++++++++end;
++++++++if+not+(rfReplaceAll+in+Flags)+then+exit;
++++++++inc(P,PatLength);
++++++++inc(d,PatLength);
++++++++PrevP:=P-1;
++++++end+else+begin
++++++++for+i:=PrevP%2B1+to+Length(S)+do+begin
++++++++++c%5E:=d%5E;
++++++++++inc(c);+inc(d);
++++++++end;
++++++end;
++++until+p=0;
++end;
end;|code-block|syntax|javascript|5309713|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

it's work like charm so fast trust it

<pre><code> Function NewStringReplace(const S, OldPattern, NewPattern: string; Flags: TReplaceFlags): string;
var
 OldPat,Srch: string; // Srch and Oldp can contain uppercase versions of S,OldPattern
 PatLength,NewPatLength,P,i,PatCount,PrevP: Integer;
 c,d: pchar;
begin
 PatLength:=Length(OldPattern);
 if PatLength=0 then begin
 Result:=S;
 exit;
 end;

 if rfIgnoreCase in Flags then begin
 Srch:=AnsiUpperCase(S);
 OldPat:=AnsiUpperCase(OldPattern);
 end else begin
 Srch:=S;
 OldPat:=OldPattern;
 end;

 PatLength:=Length(OldPat);
 if Length(NewPattern)=PatLength then begin
 //Result length will not change
 Result:=S;
 P:=1;
 repeat
 P:=PosEx(OldPat,Srch,P);
 if P&gt;0 then begin
 for i:=1 to PatLength do
 Result[P+i-1]:=NewPattern[i];
 if not (rfReplaceAll in Flags) then exit;
 inc(P,PatLength);
 end;
 until p=0;
 end else begin
 //Different pattern length -&gt; Result length will change
 //To avoid creating a lot of temporary strings, we count how many
 //replacements we're going to make.
 P:=1; PatCount:=0;
 repeat
 P:=PosEx(OldPat,Srch,P);
 if P&gt;0 then begin
 inc(P,PatLength);
 inc(PatCount);
 if not (rfReplaceAll in Flags) then break;
 end;
 until p=0;
 if PatCount=0 then begin
 Result:=S;
 exit;
 end;
 NewPatLength:=Length(NewPattern);
 SetLength(Result,Length(S)+PatCount*(NewPatLength-PatLength));
 P:=1; PrevP:=0;
 c:=pchar(Result); d:=pchar(S);
 repeat
 P:=PosEx(OldPat,Srch,P);
 if P&gt;0 then begin
 for i:=PrevP+1 to P-1 do begin
 c^:=d^;
 inc(c); inc(d);
 end;
 for i:=1 to NewPatLength do begin
 c^:=NewPattern[i];
 inc(c);
 end;
 if not (rfReplaceAll in Flags) then exit;
 inc(P,PatLength);
 inc(d,PatLength);
 PrevP:=P-1;
 end else begin
 for i:=PrevP+1 to Length(S) do begin
 c^:=d^;
 inc(c); inc(d);
 end;
 end;
 until p=0;
 end;
end;
</code></pre>

I am using StringReplace to replace &amp;gt and &amp;lt by the char itself in a generated XML like this:

<pre><code>StringReplace(xml.Text,'&amp;gt;','&gt;',[rfReplaceAll]) ;
StringReplace(xml.Text,'&amp;lt;','&lt;',[rfReplaceAll]) ;
</code></pre>

The thing is it takes way tooo long to replace every occurence of &amp;gt.

Do you purpose any better idea to make it faster?

StringReplace alternatives to improve performance

33 天实现自己的 AI 进化论？发文瓜分机械键盘、耳机等万元奖池！点击参加活动：<a href="https://cloud.tencent.com/developer/article/2503022" target="_blank">https://cloud.tencent.com/developer/article/2503022</a> 
 <img src="https://qcloudimg.tencent-cloud.cn/raw/01543e0407db10898a7ee9f420794432.jpg"/>

技术创作特训营有奖征文

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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文章&问答评论现已支持表情

我在生成的StringReplace中使用字符本身替换>和<，如下所示：StringReplace(xml.Text,'&gt;','>',[rfReplaceAll]) ;StringReplace(xml.Text,'&lt;','<',[rfReplaceAll]) ;问题是要用很长的时间来替换所有出现的>。你有没有更好的主意让它变得更快？

问用于提高性能的StringReplace替代方案
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