String and StringBuilder - A Common Mistake

Posted Date: 21 Sep 2007	Resource Type: Articles	Category: .NET Framework
Author: Muhammad Zeeshanuddin Khan	Member Level: Bronze
Rating:	Points: 10

Introduction

Everyone needs the type String in his daily programming. In addition, most of people do a common mistake to choose between String and StringBuilder.

Wrong Approach


String mySentence = null;
mySentence +=  "I";
mySentence +=  " ";
mySentence +=  "am";
mySentence +=  " ";
mySentence +=  "writing";
mySentence +=  " ";
mySentence +=  "this";
mySentence +=  " ";
mySentence +=  "interesting";
mySentence +=  " ";
mySentence +=  "article.";

This is not a good approach to deal with String because String is immutable. Therefore, every time when you concatenate the new value a new instance will be made and it will make a great performance loss if concatenation will be done many times.

Right Approach


System.Text.StringBuilder mySentence = new System.Text.StringBuilder();
mySentence.Append("I");
mySentence.Append(" ");
mySentence.Append("am");
mySentence.Append(" ");
mySentence.Append("writing");
mySentence.Append(" ");
mySentence.Append("this");
mySentence.Append(" ");
mySentence.Append("interesting");
mySentence.Append(" ");
mySentence.Append("article.");

The above code will do the same that the wrong approach did but it will lead to the great Performance boost.

Summary

Both approaches are resulting in same manner. You will not see a big difference in one look. However, remember when your code is serving for many requests the above right approach will definitely give you a performance boost.

So remember when you do not want to concatenate then surely use the String and when you have to deal with multiple concatenations then definitely use StringBuilder.

Responses

Author: Vasudevan Deepak Kumar 21 Sep 2007 Member Level: Diamond Points : 0

I would just like to add this comprehensive discussion thread on the topic:

http://www.thescripts.com/forum/thread103955.html

Deepak

Author: latha reddy 04 Oct 2007 Member Level: Gold Points : 0

nice article

Author: latha reddy 04 Oct 2007 Member Level: Gold Points : 0

nice article

Author: poorni 11 Oct 2007 Member Level: Bronze Points : 0

clearly explained..thanx

Author: Puja Sharma 24 Sep 2008 Member Level: Gold Points : 2

Thanks for the well explaind article.
Using stringbuidler instead of strings really improves the performance.

Varun

Author: Prakash Laxman kharvi 24 Sep 2008 Member Level: Silver Points : 1

Use of string builder is one of the best programming practices that every developer should incorporate.

Author: Venkat 06 Oct 2008 Member Level: Silver Points : 0

hi
Really good 1

Author: Darko 06 Oct 2008 Member Level: Bronze Points : 1

This is nice article,
But mySentence is StringBuilder object, so in order to use it as string u must add mySentence.ToString();

Author: Darko 06 Oct 2008 Member Level: Bronze Points : 1

This is nice article,
But mySentence is StringBuilder object, so in order to use it as string u must add mySentence.ToString();

Author: Roopesh Babu Valluru 14 Oct 2008 Member Level: Gold Points : 1

good exapmle man...many knew this but dont know how to use in real time...i think from here onwards they wil try to...

Thx a lot...

Author: Robin Thomas 18 Apr 2009 Member Level: Gold Points : 1

Check this . a String vs StringBuilder performance test

http://www.robinthomas.in/dotnet/stringbuilder-vs-string-concatenations/

Author: greeny_1984 19 Apr 2009 Member Level: Diamond Points : 0

Hi,

Learned a new thing today.

Thanks for sharing the information with us.

Author: sangeetha 28 May 2009 Member Level: Gold Points : 2

System.String is immutable. System.StringBuilder was designed with the purpose of having a mutable string where a variety of operations can be performed.

1.In stringBuilder, automatically increase and decrease size of string object whenever add elements and delete elements .Where in string , it is fixed size .
2.StringBuilder can performe a insert(),Delete(),Reverse(),Sort() operations etc and we can create multiple instances .Where as String , It can't perfome .
3.StringBuilder takes enough memory for variable .Where as String can't perform

Author: shital umare 13 Jun 2009 Member Level: Silver Points : 1

String is immutable (readonly)i.e every time new string object will be created for each opertion while StringBuilder is mutable,and give u more operation to perform without creating the new object

regards
-Shital

Author: Prasoon Kumar 15 Jun 2009 Member Level: Silver Points : 2

Hi
Good Article ..But More Explanation could have been

added .

But first of all let us make sure when there is a choice of string builder and string comes.

Choice of String and String Builder becomes essential if there is a lot operation involving string.Else essentially both will result into same kind of performance.

But if there is a lot operation involving string , then we are bound to make a choice among the two.

If more operation involving the same string is string is there then we should use String Builder.

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