StringBuilder.Append Method (String, Int32, Int32)
Appends a copy of a specified substring to this instance.
Assembly: mscorlib (in mscorlib.dll)
'Declaration Public Function Append ( _ value As String, _ startIndex As Integer, _ count As Integer _ ) As StringBuilder
- Type: System.String
The string that contains the substring to append.
- Type: System.Int32
The starting position of the substring within value.
- Type: System.Int32
The number of characters in value to append.
Return ValueType: System.Text.StringBuilder
A reference to this instance after the append operation has completed.
value is Nothing, and startIndex and count are not zero.
count less than zero.
startIndex less than zero.
startIndex + count is greater than the length of value.
Enlarging the value of this instance would exceed MaxCapacity.
This method appends the specified range of characters in value to the current instance. If value is Nothing and startIndex and count are both zero, no changes are made.
The method modifies the existing instance of this class; it does not return a new class instance. Because of this, you can call a method or property on the existing reference and you do not have to assign the return value to a StringBuilder object, as the following example illustrates.
Dim str As String = "First;George Washington;1789;1797" Dim index As Integer = 0 Dim sb As New System.Text.StringBuilder() Dim length As Integer = str.IndexOf(";"c, index) sb.Append(str, index, length).Append(" President of the United States: ") index += length + 1 length = str.IndexOf(";"c, index) - index sb.Append(str, index, length).Append(", from ") index += length + 1 length = str.IndexOf(";"c, index) - index sb.Append(str, index, length).Append(" to ") index += length + 1 sb.Append(str, index, str.Length - index) Console.WriteLine(sb) ' The example displays the following output: ' First President of the United States: George Washington, from 1789 to 1797
The capacity of this instance is adjusted as needed.Notes to Callers
In the .NET Framework 4 and the .NET Framework 4.5, when you instantiate the StringBuilder object by calling the StringBuilder(Int32, Int32) constructor, both the length and the capacity of the StringBuilder instance can grow beyond the value of its MaxCapacity property. This can occur particularly when you call the Append and AppendFormat methods to append small strings.