Re: Stringbuilder vs Strings
- From: Maverick <Moty.Mi@xxxxxxxxx>
- Date: 9 May 2007 08:35:01 -0700
On May 9, 6:02 pm, "Nicholas Paldino [.NET/C# MVP]"
<m...@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
It should be said that you should use StringBuilder to concatenate when
you don't exactly know how many strings you are going to concatenate. The
best example is when you have N number of strings and you need to append it
all together in a loop.
If you have a known number of strings, then using the concatenation
operator will work just fine, as it will compile to a call to the static
Concat method on the string class, which is very fast (it pre-allocates the
return buffer, and then does a memory copy of the strings into the
appropriate locations in the return buffer).
Hope this helps.
--
- Nicholas Paldino [.NET/C# MVP]
- m...@xxxxxxxxxxxxxxxxxxxxxxxxxxx
"Andy" <a...@xxxxxxxxxxxxxxxxxx> wrote in message
news:1178718261.520466.20550@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On May 9, 9:39 am, Dara P <D...@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Can some one suggest me as why StringBuilder class is better than
Strings?
Its not better, it serves a different purpose. Use StringBuilder when
you have a lot of strings to concatinate, as the SB performs
concatination and other string manipulation operations faster than
using a standard string class.
Hello,
String class is immutable. Meaning any changes made to the reference
you have to a String object (such as concatenations), will be made on
a copy of the reference. Thus, as Nicholas mentioned, N strings
concatenations will allocate N strings for each concatenation.
StringBuilder uses double capacity allocation method, decreasing
allocation performance issues and assuring O(1) allocation complexity,
and it's better for multiple changes on a single string based objects
for the reasons mentioned above.
The following example will be much better using StringBuilder:
// This method will create almost 100000 String instances
String s = "MyName";
for( int i=0; i<100000; ++i)
s+=i.ToString();
// This will use only one instance and will allocate the space needed
for each append, efficiently. Much much better..
StringBuilder sb = new StringBuilder(s);
for( int i=0; i<100000; ++i)
sb.Append(i.ToString());
You can even make it better if you can predict the capacity prior to
making the changes. This will make sure allocation is made only when
necessary.
Hope it helps :)
.
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