C# 0 The Complete Reference

PART II

C h a p t e r   2 2 :  

S t r i n g s   a n d   F o r m a t t i n g    

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of methods format data, including 

Console.WriteLine( )

,

String.Format( )

, and the 

ToString( )

method defined for the numeric structure types. The same approach to formatting is used by 

all three; once you have learned to format data for one, you can apply it to the others.

Formatting Overview

Formatting is governed by two components: 

format specifiers

 and 

format providers.

 The form 

that the string representation of a value will take is controlled through the use of a format 

specifier. Thus, it is the format specifier that dictates how the human-readable form of the 

data will look. For example, to output a numeric value using scientific notation, you will 

use the E format specifier.

In many cases, the precise format of a value will be affected by the culture and 

language in which the program is running. For example, in the United States, money is 

represented in dollars. In Europe, money is represented in euros. To handle the cultural 

and language differences, C# uses format providers. A format provider defines the way 

that a format specifier will be interpreted. A format provider is created by implementing 

the

IFormatProvider

 interface, which defines the 

GetFormat( )

 method. Format providers 

are predefined for the built-in numeric types and many other types in the .NET Framework. 

In general, you can format data without having to worry about specifying a format 

provider, and format providers are not examined further in this book.

To format data, include a format specifier in a call to a method that supports formatting. 

The use of format specifiers was introduced in Chapter 3, but is worthwhile reviewing here. 

The discussion that follows uses