Where to Place the Declarations | Unlocking Microsoft C# V 2.0 Programming Secrets (Wordware Applications Library)

Overview

This chapter discusses the data types you will use in Visual Studio C# and their declarations.

A Common Language Specification (CLS) now exists for C#, a specification initially written by Microsoft but approved by most international computer committees . The following table shows the CLS-compliant data types in Visual Studio C#:

byte	0 minimum, 255 maximum; described in System.Byte.
short	- 32,768 minimum, 32,767 maximum; described in System.Int16.
int	- 2,147,483,648 minimum, 2,147,483,647 maximum; described in System.Int32.
long	- 9,223,372,036,854,775,808 minimum, 9,223,372,036,854,775,807 maximum; described in System.Int64.
string	0 minimum, no maximum; described in System.String.
char	0 minimum, no maximum; described in System.Char. One byte (8 bits) if ASCII, two bytes (16 bits) if Unicode (which provides for characters in languages such as Japanese).
bool	Either true or false; described in System.Bool.
float	32 bits ” 23 bits for the number (7 digits), 8 bits for the exponent, and 1 sign bit; described in System.Single.
double	64 bits ” 52 bits for the number (15 to 16 digits), 11 bits for the exponent, and 1 sign bit; described in System.Double.
decimal	102 bits ” 96 bits for an integer number, 5 bits for a scaling factor, and 1 sign bit. For example, the integer number 1234567 with a scaling factor of 3 becomes 122334.567; described in System.Decimal.

Note

Since a decimal point may appear in both the decimal data type and the float/double data types, it may be necessary to mark a number with either an m for decimal (like the first letter in money ) or an f for float. If a number is unmarked (and has a decimal point in it), the compiler will assume that the number is a double.

Here are some examples:

 decimal decDollars = 101.67m;

If the letter m is removed from the end of 101.67, the compiler assumes the number is a double. Then, to place the number into a decimal named decDollars, the number is converted from a double to a decimal. With the m affixed to the number 101.67, the compiler knows that the number is a decimal.

 double dblDollars = 101.7f;

The f at the end of the number confirms to the compiler that this is indeed a float number. However, if you remove the f (which stands for floating point), the compiler assumes that the number is a double anyway.

Since the double is the default, we recommend that you perform all floating-point arithmetic using double.

You will probably do 99.9 percent of your C# work using three data types: int, double, and string. If you are a finance person you will probably add a fourth, decimal.

Table of content

Unlocking Microsoft C# V 2.0 Programming Secrets (Wordware Applications Library)

ISBN: 1556220979
EAN: 2147483647

Year: 2005
Pages: 129

Authors: Richard Braden

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