StringBuilder.Append Method (String, Int32, Int32)

[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]

Appends a copy of a specified substring to the end of this instance.

Namespace: System.Text
Assembly: mscorlib (in mscorlib.dll)

Syntax

Public Function Append ( _
    value As String, _
    startIndex As Integer, _
    count As Integer _
) As StringBuilder
public StringBuilder Append(
    string value,
    int startIndex,
    int count
)

Parameters

  • startIndex
    Type: System..::.Int32
    The starting position of the substring within value.

Return Value

Type: System.Text..::.StringBuilder
A reference to this instance after the append operation has completed.

Exceptions

Exception Condition
ArgumentNullException

value is nullNothingnullptra null reference (Nothing in Visual Basic), and startIndex and count are not zero.

ArgumentOutOfRangeException

count less than zero.

-or-

startIndex less than zero.

-or-

startIndex + count is greater than the length of value.

-or-

Enlarging the value of this instance would exceed its maximum capacity.

Remarks

This method appends the specified range of characters in value to the current instance. If value is nullNothingnullptra null reference (Nothing in Visual Basic) and startIndex and count are both zero, no changes are made.

The Append 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)
outputBlock.Text += sb.ToString() + Environment.NewLine
' The example displays the following output:
'    First President of the United States: George Washington, from 1789 to 1797      
string str = "First;George Washington;1789;1797";
int index = 0;
System.Text.StringBuilder sb = new System.Text.StringBuilder();
int length = str.IndexOf(';', index);      
sb.Append(str, index, length).Append(" President of the United States: ");
index += length + 1;
length = str.IndexOf(';', index) - index;
sb.Append(str, index, length).Append(", from ");
index += length + 1;
length = str.IndexOf(';', index) - index;
sb.Append(str, index, length).Append(" to ");
index += length + 1;
sb.Append(str, index, str.Length - index);
outputBlock.Text += sb + Environment.NewLine;
// 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.

Version Information

Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Platforms

Windows Phone

See Also

Reference

StringBuilder Class

Append Overload

System.Text Namespace

String