Greg Pierce's blog

10 Responses

1. Hi Greg, love the String class and have subscribed to your RSS.

   It’s really helped with something I was doing.

   I reckon there’s a bug or 2 (depending on your understanding of strscan) in the replaceAll method:

   pos = strscan( s, findStr, pos + strlen( replStr ), strlen( s ) );
   – 3rd arg. Shouldn’t this be pos + strlen(findStr) otherwise if replStr is longer than findStr and findStr occurs close together we’ll skip over the 2nd quick occurrence.
   – 4th arg should be strlen(s) – (pos + strlen(replStr)) ?

   Anyhoo, I was using this on a mega string (150,000 char long result from an xsl transform) with lots of occurrences of the findStr in it and it was pretty darned slow. Caching the strlens in replaceAll saved about 10% but that was still quite slow.

   There’s probably all sorts of reasons why the following shouldn’t be used but according to the profiler it’s about 40% quicker:

   static str replaceAllTest2( str s, str findStr, str replStr)
   {
   int findStrLen = strlen(findStr);
   int sLen = strlen(s);
   int pos = strscan(s, findStr, 1, sLen);

   str opStr = “”;
   int lastPos = 1;
   ;

   while(pos > 0)
   {
   opStr += substr(s, lastPos, pos – lastPos);
   opStr += replStr;
   lastPos = pos + findStrLen;

   pos = strscan(s, findStr, lastPos, sLen – lastPos);
   }
   if (lastPos != sLen)
   {
   opStr += substr(s, lastPos, sLen – lastPos);
   }

   return opStr;
   }

   It’d be interesting to write a C# version and try that out for speed but deadlines threaten

   Cheers

   Chris Rothery

   chrisroth — July 6, 2007 @ 10:14 am

2. Hey, Chris, thanks for the comments. I’d imagine any of these would be pretty slow on a large string. I made on efforts to optimize — and, frankly, X++ isn’t a real smoker.

   I’ll take a look at the bugs. I think I may have made some changes since the version that’s up here — I probably need to update. If you’re on AX v4, you should look at using .NET directly from X++. You’re manipulations will be a lot quicker.

   Of course, I also am wondering why you’re doing string manipulation on the results of an XSL transform — maybe you should look at tweaking your stylesheet to get the results you want?

   greg.

   greg — July 9, 2007 @ 9:09 pm

3. Thanks for the reply Greg.

   I might be using a rocket launcher to kill a gnat but the reason I’ve ended up doing what I’m doing is to interface with a legacy system that has a fixed file format (feel free to skip to the bottom juicy bit now).

   I’m using AX 4.0 and have written some classes to extend AIF file system adapter so that once the xml file pops out, we can transform that xml into the specific format (AIF pipeline xsl transforms were causing trouble with needing to remain xml in format and match schemas etc).

   That’s all working but the specific format we’re generating has tags with in it. To get my xsl file to import into the repository we had to use < etc to stop it complaining that our xsl file was rubbish. That meant that those replacements came out in the final file rather than etc.

   In the cold light of day, I agreed with you that I should try and sort the xsl but try as I might I couldn’t so I went back to processing the string result of the transform before writing it.

   Long story short it’s now working beautifully (and ridiculously quickly!) using .Net directly (something I am only just getting into and was scared of but am going go persue now I’ve seen these results):

   /*
   replace the all occurances of “findStr” with “replStr” in “s”
   */
   static str replaceAllTest3( str s, str findStr, str replStr)
   {
   // BP Deviation Documented
   System.Text.StringBuilder sb = new System.Text.StringBuilder(s);
   ;

   sb.Replace(findStr, replStr);
   return sb.ToString();
   }

   According to the Dynamics profiler, the original replaceAll clocked about 3 million ‘ticks’. I got that down by about 40% but the Test3 above clocks in at a mere 33,000 ticks!!!

   Amazed, happy, you name it, I’m experiencing the emotion right now

   Thanks for your help and keep up the good work

   Chris

   chrisroth — July 10, 2007 @ 4:24 am

4. Oh and…

   I’m 99% sure I was being a moron on my 1st comment re the 3rd arg to the strscan line and it should be ‘pos + strlen(replStr)’.

   

   chrisroth — July 10, 2007 @ 5:15 am

5. Thanks a whole lot for the classes, Greg! You’ve just spared me a bunch of time. Thanks again. Greets from Hungary

   webmotion — June 23, 2008 @ 6:09 am

6. I searched on google and I had a hard time located the right info….until I found your blog.

   gun pos — April 25, 2009 @ 12:45 pm

7. Surly:

   static str dbsReplaceString(str _inString, str _search, str _replace)
   {
   int pos = strScan(_inString, _search, 1, strLen(_inString))
   ;
   if (!pos)
   return _inString;
   else
   return subStr(_inString, 1, pos – 1) + _replace + substr(_inString, pos + strLen(_search), strLen(_inString));
   }

   Or am I missing something?

   TumbleWeed — January 27, 2010 @ 7:47 am

8. I meant:

   static str dbsReplaceString(str _inString, str _search, str _replace)
   {
   int pos = strScan(_inString, _search, 1, strLen(_inString))
   ;
   if (!pos)
   return _inString;
   else
   return dbsLib::dbsReplaceString(subStr(_inString, 1, pos – 1) + _replace + substr(_inString, pos + strLen(_search), strLen(_inString)), _search, _replace);
   }

   TumbleWeed — January 27, 2010 @ 7:55 am

9. thanks from Mexico

   Daniel — June 7, 2010 @ 9:47 pm

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