Ah. Did some digging around and you're right that StringBuilder.ToString() doesn't allocate a new string - I'd assumed that it would do. That would take your technique of using StringBuilder down to 1 or 2 string allocations, same as Greg's direct approach, meaning there's little to choose between them.
And yeah I'd agree that if you're doing this with strings from a database then a stored procedure is likely to be better anyway. Simon --------------------------------------------------------------- Simon Robinson http://www.SimonRobinson.com --------------------------------------------------------------- ----- Original Message ----- From: "Erick Thompson" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Friday, May 03, 2002 2:28 AM Subject: Re: [DOTNET] String concatenation performance > Simon, > > I only see two string copies. When the StringBuilder is created, the string > is copied in (I believe, but I could see an internal optimization that > wouldn't copy it). Then, the Insert methods and replace method all act on > the StringBuilder, which should occur in-place. The final ToString() method > of the StringBuilder is a zero cost operation, as it just returns a > reference to the char array contained in the StringBuilder as a string. > > But, I think you are right about Greg's method being more efficient, but not > by much. > > sb.Insert(2,sb.Replace("'", "''").ToString()); > > I think that this method may cause the string returned by sb.Replace("'", > "''").ToString() to be copied into the char array in the StringBuilder. If > it does, then that makes two string copies, equal to Gregs method. But I > think that the overhead of the additional calls to Insert probably make the > performance a little worse overall. > > But I think someone else said it best when they said that it shouldn't make > that much difference either way, and that a SqlParameter should be used > instead :) > > Erick > > > ----- Original Message ----- > From: "Simon Robinson" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Sent: Thursday, May 02, 2002 5:59 PM > Subject: Re: [DOTNET] String concatenation performance > > > > Erick > > > > Hate to say this but I'm afraid I don't agree with that. I think that > > Greg had probably got the most efficient method. > > > > Greg uses a Replace followed by a string concatenation. > > That means he'll have to copy the string either once > > or twice: Twice if the > > call to String.Replace() needs to do anything, or just one > > allocation if the string contains no single quotes and the > > call to Replace() has no effect. > > > > By contrast, using a StringBuilder, > > you will always get at least two new string copy operations > > - one to copy the original string into the StringBuilder object, > > and another one to copy it back out again. Not only that, > > but your call to String.Replace() will give a third string copy > > if any single quotes do need to be replaced. Either way, > > using a StringBuilder gives one more string copy than > > Greg's method of manipulating the string. > > > > > > Simon > > > > --------------------------------------------------------------- > > Simon Robinson > > http://www.SimonRobinson.com > > --------------------------------------------------------------- > > ----- Original Message ----- > > From: "Erick Thompson" <[EMAIL PROTECTED]> > > To: <[EMAIL PROTECTED]> > > Sent: Friday, May 03, 2002 1:37 AM > > Subject: Re: [DOTNET] String concatenation performance > > > > > > > This should be faster. I'm not sure about the Insert method as far as > > > performance goes but this method shouldn't cause any unneeded string > > > allocations. However, I'm sure it could be improved on. > > > > > > public static string DoQuotes(string sqlParam) { > > > System.Text.StringBuilder sb = new > > > System.Text.StringBuilder(sqlParam.Length + 2); > > > if (sqlParam.IndexOf("'") > 0) { > > > sb.Insert(2,sb.Replace("'", "''").ToString()); > > > } else { > > > sb.Insert(2, sqlParam); > > > } > > > sb.Insert(1, "'"); > > > sb.Append("'"); > > > return sb.ToString(); > > > } > > > > > > Erick > > > > > > ----- Original Message ----- > > > From: "Greg Gates" <[EMAIL PROTECTED]> > > > To: <[EMAIL PROTECTED]> > > > Sent: Thursday, May 02, 2002 5:24 PM > > > Subject: [DOTNET] String concatenation performance > > > > > > > > > > Hello everyone: > > > > > > > > I have the following helper method to format sql string parameters: > > > > > > > > public static string DoQuotes(string sqlParam) > > > > { > > > > if (sqlParam.IndexOf("'") > 0) > > > > { > > > > sqlParam = sqlParam.Replace("'","''"); > > > > } > > > > > > > > return "'" + sqlParam + "'"; > > > > } > > > > > > > > > > > > Is there a better way, performance-wise? > > > > > > > > thanks, Greg > > > > > > > > You can read messages from the DOTNET archive, unsubscribe from > DOTNET, > > or > > > > subscribe to other DevelopMentor lists at http://discuss.develop.com. > > > > > > You can read messages from the DOTNET archive, unsubscribe from DOTNET, > or > > > subscribe to other DevelopMentor lists at http://discuss.develop.com. > > > > > > > You can read messages from the DOTNET archive, unsubscribe from DOTNET, or > > subscribe to other DevelopMentor lists at http://discuss.develop.com. > > > > You can read messages from the DOTNET archive, unsubscribe from DOTNET, or > subscribe to other DevelopMentor lists at http://discuss.develop.com. > You can read messages from the DOTNET archive, unsubscribe from DOTNET, or subscribe to other DevelopMentor lists at http://discuss.develop.com.
