blocks|key|1196058|text|创建新的StringBuilder。旧的维护与其相关的资源(例如，最大长度的缓冲区)，这些资源最好被垃圾回收。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1196059|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Create the new StringBuilder. The old one maintains resources associated with it (buffer of maximum length, for example) that are best just garbage collected away.

blocks|key|1196103|text|在.NET+4.0中，您可以调用sb.Clear()，但在旧版本中，您应该设置sb.Length+=+0。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1196104|.NET+4.0中添加了Clear()方法。|1196105|entityMap^0|G|A|13|D|0|C|7|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]|$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|R|8|@]|D|@]|E|$]]]|I|$]]

In .NET 4.0 you can call <code>sb.Clear()</code> but in older versions you should set <code>sb.Length = 0</code>.

The <code>Clear()</code> method was added in .NET 4.0.

blocks|key|1411478|text|我认为你过早地进行了优化。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1411479|我敢打赌，做sb.Length=0;是避免创建另一个对象并将另一个对象放在一边等待GC最终收集的最快方法。|offset|length|style|CODE|1411480|我认为创建一个新的StringBuilder是解决内存问题的最好办法。而设置sb.Length将是解决速度问题的最佳选择。|1411481|entityMap^0|0|6|C|0|12|9|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|M|8|@$D|N|E|O|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|P|8|@$D|Q|E|R|F|G]]|9|@]|A|$]]|$1|J|3|-4|5|6|7|S|8|@]|9|@]|A|$]]]|K|$]]

I think you are doing premature optimization.

I would bet that doing <code>sb.Length=0;</code> would be the fastest to keep from creating another object and placing another object aside for GC to eventually collect. 

I think creating a new StringBuilder would be the best shot for memory concerns. and setting <code>sb.Length</code> would be the best shot for speed concerns..

blocks|key|1196212|text|如果您正在寻找减少内存使用，我会使用CLR事件探查器来检查您的StringBuilder对象在其生命周期中使用了多少内存，使用其他人已经在上面描述的方法。然后，您可以确信您选择的选项适合您的需求，并且正在释放您需要的资源。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1196213|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

If you are looking to reduce memory usage I would use the CLR Profiler to check how much memory your StringBuilder objects are using through their lifecycle using the methods others have described above. Then you can satisfy yourself that the option you choose is suitable for your needs and is releasing the resources you need it to.

blocks|key|1411553|text|在.NET框架中，在StringBuilder类中引入了4个新方法。方法名称为"Clear“。此方法可帮助您清除或删除StringBuilder对象中的值或数据。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1411554|这里有一个这样的例子。|1411555|++++System.Text.StringBuilder+objSB+=+new+System.Text.StringBuilder();
++++//Append+values
++++objSB.Append("This+is+.Net+Blog.");
++++objSB.Append("You+can+get+latest+C#+Tips+over+here.");

++++//Display+on+screen
++++Response.Write(objSB.ToString());
++++Response.Write(" ");

++++//Clear+object+using+Clear+method
++++objSB.Clear();

++++//Append+another+values
++++objSB.Append("This+blog+is+very+useful+for+.Net+Beginners");

++++Response.Write("After+Clear ");
++++//Display+on+screen
++++Response.Write(objSB.ToString());|code-block|syntax|javascript|1411556|entityMap^0|A|D|1N|D|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|T|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|U|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|V|8|@]|D|@]|E|$]]]|N|$]]

In .NET Framework 4 new methods were introduced in <code>StringBuilder</code> class. Method name is "Clear". This method helps you to clear or remove values or data from <code>StringBuilder</code> objects.

Here is example for this.

<pre><code> System.Text.StringBuilder objSB = new System.Text.StringBuilder();
 //Append values
 objSB.Append("This is .Net Blog.");
 objSB.Append("You can get latest C# Tips over here.");

 //Display on screen
 Response.Write(objSB.ToString());
 Response.Write("&lt;br/&gt;&lt;br/&gt;");

 //Clear object using Clear method
 objSB.Clear();

 //Append another values
 objSB.Append("This blog is very useful for .Net Beginners");

 Response.Write("After Clear&lt;br/&gt;&lt;br/&gt;");
 //Display on screen
 Response.Write(objSB.ToString());
</code></pre>

blocks|key|1196302|text|只需调用Clear()方法，只需设置length+=0，如果想节省内存，我们也可以设置also+=0|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1196303|public+StringBuilder+Clear()+{
++++++++this.Length+=+0;
++++++++return+this;
+}|code-block|syntax|javascript|1196304|参考:在referencesource.microsoft.com中|offset|length|1196305|entityMap|0|LINK|mutability|MUTABLE|url|https://referencesource.microsoft.com/#mscorlib/system/text/stringbuilder.cs,adf60ee46ebd299f^0|0|0|4|T|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

Just call Clear() method just set length = 0 ,
We can set Capacity = 0 also, if we want to save memory

<pre><code>public StringBuilder Clear() {
 this.Length = 0;
 return this;
 }
</code></pre>

Ref: In <a href="https://referencesource.microsoft.com/#mscorlib/system/text/stringbuilder.cs,adf60ee46ebd299f" rel="nofollow noreferrer">referencesource.microsoft.com</a>

blocks|key|1196319|text|//+P.S.+to+be+ultra+efficient+
//+make+a+good+guess+at+the+initial+allocation+too+!!!!
int+PerWhatever_SizeEstimate+=+4;+//+a+guess+of+average+length...+you+known+your+data
StringBuilder+sb+=+new+StringBuilder(+whateverlist.Length+*+PerWhatever_SizeEstimate);

//+reallocation+needed?+
//+if+you+want+to+be+efficient+speed+and+memory+wise...+
sb.Length+=+0;++//+rest+internal+index+but+don't+release/resize+memory
//+if+a+...BIG...+difference+in+size
if(+whatever2.Length+<+whatever.Length+*+2/3++
+%7C%7C+whatever2.Length+>+whatever.Length+*+1.5)
{
++++//scale+capacity+appropriately
++++sb.Capaciy+=+sb.Capacity+*+whatever2.Length+/+whatever.Length;
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1196320|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>// P.S. to be ultra efficient 
// make a good guess at the initial allocation too !!!!
int PerWhatever_SizeEstimate = 4; // a guess of average length... you known your data
StringBuilder sb = new StringBuilder( whateverlist.Length * PerWhatever_SizeEstimate);

// reallocation needed? 
// if you want to be efficient speed and memory wise... 
sb.Length = 0; // rest internal index but don't release/resize memory
// if a ...BIG... difference in size
if( whatever2.Length &lt; whatever.Length * 2/3 
 || whatever2.Length &gt; whatever.Length * 1.5)
{
 //scale capacity appropriately
 sb.Capaciy = sb.Capacity * whatever2.Length / whatever.Length;
}
</code></pre>

I would like to ask what you think is the best way (lasts less / consumes less resources) to clear the contents in order to reuse a StringBuilder. Imagine the following scenario:

<pre><code>StringBuilder sb = new StringBuilder();
foreach(var whatever in whateverlist)
{
 sb.Append("{0}", whatever);
}

//Perform some stuff with sb

//Clear stringbuilder here

//Populate stringbuilder again to perform more actions
foreach(var whatever2 in whateverlist2)
{
 sb.Append("{0}", whatever2);
}
</code></pre>

And when clearing StringBuilder I can think of two possibilities:

<pre><code>sb = new StringBuilder();
</code></pre>

or

<pre><code>sb.Length = 0;
</code></pre>

What is the best way to clear it and why? 

Thank you.

EDIT: I ment with current .NET 3.5 version.

best way to clear contents of .NET's StringBuilder

我想问一下，为了重用StringBuilder，您认为清除内容的最佳方式(持续时间较短/消耗较少的资源)是什么？想象一下下面的场景：StringBuilder sb = new StringBuilder();foreach(var whatever in whateverlist){  sb.Append("{0}"...

问清除.NET StringBuilder内容的最佳方法
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