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StringBuilder.Append Method (String, Int32, Int32)

Updated: January 2011

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

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

public StringBuilder Append(
	string value,
	int startIndex,
	int count
)

Parameters

value
Type: System.String

The string that contains the substring to append.

startIndex
Type: System.Int32

The zero-based starting position of the substring within value.

count
Type: System.Int32

The number of characters in value to append.

Return Value

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

ExceptionCondition
ArgumentNullException

value is null, 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 MaxCapacity.

This method appends the specified range of characters in value to the current instance. If value is null 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.

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);
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.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

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

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

Date

History

Reason

January 2011

Expanded the Remarks section and removed the example.

Customer feedback.

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