dot.NET.Framework.Essentials.1002003,.3Ed [Electronic resources]

Hoang Lam; Thuan L. Thai

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Appendix C. Common Data Types

Each of the .NET languages can provide its own keywords for the types it supports. For example, a keyword for an integer in VB is Integer, whereas in C# or C++ it is int; a boolean is Boolean in VB, but bool in C# or C++. In any case, the integer is mapped to the class Int32, and the boolean is mapped to the class Boolean in the System namespace. Table C-1 lists all simple data types common to the .NET Framework. Non-CLS-compliant types are not guaranteed to interoperate with all CLS-compliant languages.

Table C-1. Common data types

Type

Description

Boolean

True or false.

Byte

8-bit unsigned integer: 0 to 255.

Char

Character. Unicode 16-bit character.

DateTime

Represents a date and time value.

Decimal

Can represent positive and negative values with 28 significant digits: -79,228,162,514,264,337,593,543,950,335 to 79,228,162,514,264,337,593,543,950,335 .

Double

Stores 64-bit floating-point values: -1.79769313486231570e308 to 1.79769313486231570e308.

Guid

Represents a globally unique identifier (GUID); this is stored internally as a 128-bit integer. Commonly represented as a series of lowercase hexadecimal digits in groups of 8, 4, 4, 4, and 12 digits and separated by hyphens (e.g., 382c74c3-721d-4f34-80e5-57657b6cbc27).

Int16

Stores 16-bit signed integers: -32,768 to 32,767.

Int32

Stores 32-bit signed integers: -2,147,483,648 to 2,147,483,647.

Int64

Stores 64-bit signed integers: -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807.

SByte

Represents an 8-bit signed integer. The SByte type is not CLS-compliant. -128 to 127.

Single

Represents an IEEE 754f, single precision, 32-bit value: -3.40282346638528859e38 to 3.40282346638528859e38.

String

Represents a string of Unicode characters.

UInt16

Represents a 16-bit unsigned integer. The UInt16 type is not CLS- compliant. 0 to 65,535.

UInt32

Represents a 32-bit unsigned integer. The UInt32 type is not CLS- compliant. 0 to 4,294,967,295

UInt64

Represents a 64-bit unsigned integer. The UInt64 type is not CLS- compliant. The UInt64 data type can represent positive integers with 18 significant digits: 0 to 184,467,440,737,095,551,615.

Void

Void.

Table C-2 shows a number of useful container types that the .NET Framework provides.

Table C-2. Container types

Type

Description

Array

General array construct.

ArrayList

This class implements the IList interface. The array can grow or shrink dynamically in size.

BitArray

This class represents a compact array of bit values. Each element represents a Boolean value (true/false).

HashTable

This class represents a collection of associated keys and values that are organized based on the hash code of the key.

Queue

This class represents a first-in, first-out collection construct.

SortedList

This class is similar to HashTable except that all elements are sorted by their actual keys (not hashed) and elements are accessible through either key or index.

Stack

This class represents a first-in, last-out stack construct.