David Heffernan

I don't see any reason to check that. We've long since solved this.

Not if the search string is longer than the other string. Then it's a buffer overrun. Use the version from my post.

{$APPTYPE CONSOLE} uses System.SysUtils, System.Diagnostics, System.StrUtils; function MyStartsWith(const SearchText, Text: string): Boolean; var Index, SearchTextLen: Integer; begin SearchTextLen := Length(SearchText); if SearchTextLen>Length(Text) then begin Result := False; Exit; end; for Index := 1 to SearchTextLen do if Text[Index]<>SearchText[Index] then begin Result := False; Exit; end; Result := True; end; const cMaxLoop = 10000000; cText = 'Error: Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.'; cTextNoHits = 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.'; cStartsWithShort = 'E'; cStartsWithLong = 'Error:'; var vSW: TStopWatch; i, vLen: integer; hitCount: Integer; vResult: boolean; begin Writeln('Substring exists at the start:'); // Short string Writeln('Short string:'); hitCount := 0; vSW := TStopWatch.StartNew; for i := 1 to cMaxLoop do if Copy(cText, 1, Length(cStartsWithShort)) = cStartsWithShort then Inc(hitCount); Writeln(' Copy: ' + vSW.ElapsedMilliseconds.ToString, ' ', hitCount); hitCount := 0; vSW := TStopWatch.StartNew; for i := 1 to cMaxLoop do if MidStr(cText, 1, Length(cStartsWithShort)) = cStartsWithShort then Inc(hitCount); Writeln(' MidStr: ' + vSW.ElapsedMilliseconds.ToString, ' ', hitCount); hitCount := 0; vSW := TStopWatch.StartNew; for i := 1 to cMaxLoop do if cText.StartsWith(cStartsWithShort) then Inc(hitCount); Writeln(' StartsWith: ' + vSW.ElapsedMilliseconds.ToString, ' ', hitCount); hitCount := 0; vSW := TStopWatch.StartNew; for i := 1 to cMaxLoop do if StartsStr(cStartsWithShort, cText) then Inc(hitCount); Writeln(' StartsStr: ' + vSW.ElapsedMilliseconds.ToString, ' ', hitCount); hitCount := 0; vSW := TStopWatch.StartNew; for i := 1 to cMaxLoop do if MyStartsWith(cStartsWithShort, cText) then Inc(hitCount); Writeln(' MyStartsWith: ' + vSW.ElapsedMilliseconds.ToString, ' ', hitCount); // Long string Writeln('Long string:'); hitCount := 0; vSW := TStopWatch.StartNew; for i := 1 to cMaxLoop do if Copy(cText, 1, Length(cStartsWithLong)) = cStartsWithLong then Inc(hitCount); Writeln(' Copy: ' + vSW.ElapsedMilliseconds.ToString, ' ', hitCount); hitCount := 0; vSW := TStopWatch.StartNew; for i := 1 to cMaxLoop do if MidStr(cText, 1, Length(cStartsWithLong)) = cStartsWithLong then Inc(hitCount); Writeln(' MidStr: ' + vSW.ElapsedMilliseconds.ToString, ' ', hitCount); hitCount := 0; vSW := TStopWatch.StartNew; for i := 1 to cMaxLoop do if cText.StartsWith(cStartsWithLong) then Inc(hitCount); Writeln(' StartsWith: ' + vSW.ElapsedMilliseconds.ToString, ' ', hitCount); hitCount := 0; vSW := TStopWatch.StartNew; for i := 1 to cMaxLoop do if StartsStr(cStartsWithLong, cText) then Inc(hitCount); Writeln(' StartsStr: ' + vSW.ElapsedMilliseconds.ToString, ' ', hitCount); hitCount := 0; vSW := TStopWatch.StartNew; for i := 1 to cMaxLoop do if MyStartsWith(cStartsWithLong, cText) then Inc(hitCount); Writeln(' MyStartsWith: ' + vSW.ElapsedMilliseconds.ToString, ' ', hitCount); Writeln; // Text DEOS NOT start with selected string Writeln('Substring NOT exists at the start:'); // Short string Writeln('Short string:'); hitCount := 0; vSW := TStopWatch.StartNew; for i := 1 to cMaxLoop do if Copy(cTextNoHits, 1, Length(cStartsWithShort)) = cStartsWithShort then Inc(hitCount); Writeln(' Copy: ' + vSW.ElapsedMilliseconds.ToString, ' ', hitCount); hitCount := 0; vSW := TStopWatch.StartNew; for i := 1 to cMaxLoop do if MidStr(cTextNoHits, 1, Length(cStartsWithShort)) = cStartsWithShort then Inc(hitCount); Writeln(' MidStr: ' + vSW.ElapsedMilliseconds.ToString, ' ', hitCount); hitCount := 0; vSW := TStopWatch.StartNew; for i := 1 to cMaxLoop do if cTextNoHits.StartsWith(cStartsWithShort) then Inc(hitCount); Writeln(' StartsWith: ' + vSW.ElapsedMilliseconds.ToString, ' ', hitCount); hitCount := 0; vSW := TStopWatch.StartNew; for i := 1 to cMaxLoop do if StartsStr(cStartsWithShort, cTextNoHits) then Inc(hitCount); Writeln(' StartsStr: ' + vSW.ElapsedMilliseconds.ToString, ' ', hitCount); hitCount := 0; vSW := TStopWatch.StartNew; for i := 1 to cMaxLoop do if MyStartsWith(cStartsWithShort, cTextNoHits) then Inc(hitCount); Writeln(' MyStartsWith: ' + vSW.ElapsedMilliseconds.ToString, ' ', hitCount); // Long string Writeln('Long string:'); hitCount := 0; vSW := TStopWatch.StartNew; for i := 1 to cMaxLoop do if Copy(cTextNoHits, 1, Length(cStartsWithLong)) = cStartsWithLong then Inc(hitCount); Writeln(' Copy: ' + vSW.ElapsedMilliseconds.ToString, ' ', hitCount); hitCount := 0; vSW := TStopWatch.StartNew; for i := 1 to cMaxLoop do if MidStr(cTextNoHits, 1, Length(cStartsWithLong)) = cStartsWithLong then Inc(hitCount); Writeln(' MidStr: ' + vSW.ElapsedMilliseconds.ToString, ' ', hitCount); hitCount := 0; vSW := TStopWatch.StartNew; for i := 1 to cMaxLoop do if cTextNoHits.StartsWith(cStartsWithLong) then Inc(hitCount); Writeln(' StartsWith: ' + vSW.ElapsedMilliseconds.ToString, ' ', hitCount); hitCount := 0; vSW := TStopWatch.StartNew; for i := 1 to cMaxLoop do if StartsStr(cStartsWithLong, cTextNoHits) then Inc(hitCount); Writeln(' StartsStr: ' + vSW.ElapsedMilliseconds.ToString, ' ', hitCount); hitCount := 0; vSW := TStopWatch.StartNew; for i := 1 to cMaxLoop do if MyStartsWith(cStartsWithLong, cTextNoHits) then Inc(hitCount); Writeln(' MyStartsWith: ' + vSW.ElapsedMilliseconds.ToString, ' ', hitCount); readln; end. Copy is clearly a shocker of an idea for this use. heap allocation!! Really?!!! And the other functions seem really slow. A simple for loop is around 10 times faster. I didn't capture any timings, but it's easy to do it on your machine. I also addressed a couple of issues with your benchmark code. I don't believe this is a bottleneck in your program, but you love premature optimisation with a rarely seen passion.

Make a minimal reproduction

Works fine here. Try it with a plain vanilla TListView to rule out the changes you have made.

Put the code that you don't want clients to have access to in a separate module/library/web service/etc. that is only available on your intranet.

Bookmark this: https://softwareengineering.stackexchange.com/a/80092/14432

The question really is how much security you need. What would be the consequence of somebody outside your organisation getting access to this functionality?

Sorting a reversed array is 100% from the real world. In a UI where you sort by a column ascending, and then sort by the same column descending.

Earlier in the thread you said that the original problem from the SO question was driving this topic.

Sample data might be useful. I'm amazed that you don't see the huge difference between your SO question and the code in this post. In this post you make one replacement. In the SO post you make five. That's the key issue here. And in five years you have not appreciated it.

The code in this post doesn't accurately represent the code in your app which calls StringReplace repeatedly on the same string. As per the SO question.

Your benchmarks are bogus because the real code replaces multiple strings. It is simple to make this code at least three times faster in the real setting.

I did

OK. In that case I definitely recommend the neslib parser. I myself use libyaml2 but neslib is good.

Read back in the thread. He says that it's the same code as the SO question that he is trying to make go faster.

The code is the code in the SO question which calls StringReplace multiple times.

That's not the right way to solve this. The right way is to iterate over the string once rather than 5-10 times. Why would you want to iterate over the string so many times?

It's really way easier in Python. Essentially a two liner, one to parse, and one to dump. That's how I'd do a one time conversion.

I don't know about you, but I use the best tool for the job, not the best tool written in Delphi!

Does anybody really see Dev C++ as being very useful these days? Unless I am mistaken, there are numerous IDEs now that far exceed what Dev C++ can do. Surely this is just a link about some work done on a legacy Delphi project. I can't believe the intent is to suggest that Dev C++ is relevant to C++ developers today.

Leaving aside the issues that are commented on by other, instead of if Supports(fBaseFrameClass, ISupportTask) then (fBaseFrame as ISupportTask).CheckTask; surely you need var Task: ISupportTask; ... if Supports(fBaseFrame, ISupportTask, Task) then Task.CheckTask; Two changes: Ask the implementing object rather than the class whether or not the interface is supported. Use the three argument overload of Supports so that you can get the interface while you are querying for it.

Take some time to find/write helper functions to do the sort of processing you need on these byte arrays and your code may even end up easier to read!

AnsiString is no longer like an array of bytes because of the implicit encoding conversions that happen with that type. If you really have byte array data then perhaps a byte array is what you need.

Why are you using AnsiString at all? Why aren't you using the string type?