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StringBuilder::AppendFormat Method (String, array<Object>)

Appends the string returned by processing a composite format string, which contains zero or more format items, to this instance. Each format item is replaced by the string representation of a corresponding argument in a parameter array.

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

public:
StringBuilder^ AppendFormat(
	String^ format, 
	... array<Object^>^ args
)

Parameters

format
Type: System::String

A composite format string (see Remarks).

args
Type: array<System::Object>

An array of objects to format.

Return Value

Type: System.Text::StringBuilder
A reference to this instance with format appended. Each format item in format is replaced by the string representation of the corresponding object argument.

ExceptionCondition
ArgumentNullException

format or args is nullptr.

FormatException

format is invalid.

-or-

The index of a format item is less than 0 (zero), or greater than or equal to the length of the args array.

ArgumentOutOfRangeException

The length of the expanded string would exceed MaxCapacity.

This method uses the composite formatting feature of the .NET Framework to convert the value of an object to its text representation and embed that representation in the current StringBuilder object.

The format parameter consists of zero or more runs of text intermixed with zero or more indexed placeholders, called format items, that correspond to objects in the parameter list of this method. The formatting process replaces each format item with the string representation of the corresponding object.

The syntax of a format item is as follows:

{index[,length][:formatString]}

Elements in square brackets are optional. The following table describes each element.

Element

Description

index

The zero-based position in the parameter list of the object to be formatted. If the object specified by index is nullptr, the format item is replaced by String::Empty. If there is no parameter in the index position, a FormatException is thrown.

,length

The minimum number of characters in the string representation of the parameter. If positive, the parameter is right-aligned; if negative, it is left-aligned.

:formatString

A standard or custom format string that is supported by the parameter.

NoteNote

For the standard and custom format strings used with date and time values, see Standard Date and Time Format Strings and Custom Date and Time Format Strings. For the standard and custom format strings used with numeric values, see Standard Numeric Format Strings and Custom Numeric Format Strings. For the standard format strings used with enumerations, see Enumeration Format Strings.

args represents the objects to be formatted. Each format item in format is replaced with the string representation of the corresponding object in args. If the format item includes formatString and the corresponding object in args implements the IFormattable interface, then args[index].Format(formatString, provider) defines the formatting. Otherwise, args[index].ToString(provider) defines the formatting.

If the string assigned to format is "Thank you for your donation of {0:####} cans of food to our charitable organization." and arg0 is an integer with the value 10, the return value will be "Thank you for your donation of 10 cans of food to our charitable organization."

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.

The following example demonstrates the AppendFormat method.

using namespace System;
using namespace System::Text;
using namespace System::Globalization;
void Show( StringBuilder^ sbs )
{
   Console::WriteLine( sbs );
   sbs->Length = 0;
}

int main()
{
   StringBuilder^ sb = gcnew StringBuilder;
   int var1 = 111;
   float var2 = 2.22F;
   String^ var3 = "abcd";
   array<Object^>^var4 = {3,4.4,(Char)'X'};
   Console::WriteLine();
   Console::WriteLine( "StringBuilder.AppendFormat method:" );
   sb->AppendFormat( "1) {0}", var1 );
   Show( sb );
   sb->AppendFormat( "2) {0}, {1}", var1, var2 );
   Show( sb );
   sb->AppendFormat( "3) {0}, {1}, {2}", var1, var2, var3 );
   Show( sb );
   sb->AppendFormat( "4) {0}, {1}, {2}", var4 );
   Show( sb );
   CultureInfo^ ci = gcnew CultureInfo( "es-ES",true );
   array<Object^>^temp1 = {var2};
   sb->AppendFormat( ci, "5) {0}", temp1 );
   Show( sb );
}

/*
This example produces the following results:

StringBuilder.AppendFormat method:
1) 111
2) 111, 2.22
3) 111, 2.22, abcd
4) 3, 4.4, X
5) 2,22
*/

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, 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.

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