String.Format Method (String, Object, Object, Object)

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 a string. The .NET Framework provides extensive formatting support, which is described in greater detail in the following formatting topics.

• For more information about the composite formatting feature supported by methods such as Format, AppendFormat, and some overloads of WriteLine, see Composite Formatting.

• For more information about numeric format specifiers, see Standard Numeric Format Strings and Custom Numeric Format Strings.

• For more information about date and time format specifiers, see Standard Date and Time Format Strings and Custom Date and Time Format Strings.

• For more information about enumeration format specifiers, see Enumeration Format Strings.

• For more information about formatting, see Formatting Types and Formatting Overview.

The format parameter consists of zero or more runs of text intermixed with zero or more indexed placeholders, called format items, that correspond to an object 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.

Note:
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.

The leading and trailing brace characters, '{' and '}', are required. To specify a single literal brace character in format, specify two leading or trailing brace characters; that is, "{{" or "}}".

If the value of format is, "Thank you for your purchase of {0:####} copies of Microsoft®.NET (Core Reference).", and arg0 is an Int16 with the value 123, then the return value will be:

"Thank you for your purchase of 123 copies of Microsoft®.NET (Core Reference)."

If the value of format is, "Brad's dog has {0,-8:G} fleas.", arg0 is an Int16 with the value 42, (and in this example, underscores represent padding spaces) then the return value will be:

"Brad's dog has 42______ fleas."

The following example uses the Format(String, Object, Object, Object) method to create a string that illustrates the result of a Boolean And operation with two integer values. Note that the format string includes six format items, but the method has only three items in its parameter list, because each item is formatted in two different ways.

using System;

public class Example
{
   public static void Main()
   {
      string formatString = "    {0,10} ({0,8:X8})\n" + 
                            "And {1,10} ({1,8:X8})\n" + 
                            "  = {2,10} ({2,8:X8})";
      int value1 = 16932;
      int value2 = 15421;
      string result = String.Format(formatString, 
                                    value1, value2, value1 & value2);
      Console.WriteLine(result);
   }
}
// The example displays the following output:
//                16932 (00004224)
//       And      15421 (00003C3D)
//         =         36 (00000024)

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

.NET Framework

.NET Compact Framework

XNA Framework

Reference

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