StringBuilder.Clear Method

Clear is a convenience method that is equivalent to setting the Length property of the current instance to 0 (zero).

Calling the Clear method does not modify the current instance's Capacity or MaxCapacity property.

The following example instantiates a StringBuilder object with a string, calls the Clear method, and then appends a new string.

using System;
using System.Text;

public class Class1
{
   public static void Main()
   {
      StringBuilder sb = new StringBuilder("This is a string.");
      Console.WriteLine("{0} ({1} characters)", sb.ToString(), sb.Length);

      sb.Clear();
      Console.WriteLine("{0} ({1} characters)", sb.ToString(), sb.Length);

      sb.Append("This is a second string.");
      Console.WriteLine("{0} ({1} characters)", sb.ToString(), sb.Length);
   }
}
// The example displays the following output: 
//       This is a string. (17 characters) 
//        (0 characters) 
//       This is a second string. (24 characters)

.NET Framework

.NET Framework Client Profile

Portable Class Library

.NET for Windows Store apps

Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Reference