System Namespace

Contains fundamental classes and base types that define commonly used value and reference data types, events and event handlers, interfaces, attributes, and processing exceptions.


Name Description
Public Class AppDomain Represents an application domain, which is an isolated environment in which applications run.
Public Class AppDomainUnloadedException The exception that is thrown when an attempt is made to access an unloaded application domain.
Public Class ApplicationException The exception that is thrown when a nonfatal application error occurs.
Public Class ArgumentException The exception that is thrown when one of the arguments provided to a method is not valid.
Public Class ArgumentNullException The exception that is thrown when a null reference is passed to a method that does not accept it as a valid argument.
Public Class ArgumentOutOfRangeException The exception that is thrown when the value of an argument is outside the allowable range of values, as defined by the method that was invoked.
Public Class Array Contains methods for creating, manipulating, searching, and sorting arrays. The Array class is therefore the base class for all arrays in the common language runtime (CLR).
Public Class Attribute Constitutes the base class for custom attributes.
Public Class AttributeUsageAttribute Specifies the usage of another attribute class.
Public Class CLSCompliantAttribute Indicates whether a particular program element is compliant with the Common Language Specification (CLS).
Public Class Convert Converts to and from base64-encoded strings.
Public Class Delegate Represents a delegate, which is a data structure that refers to a static method or to a class instance and an instance method of that class.
Public Class Enum Constitutes the base class for enumerations.
Public Class Environment Manages information about the operating environment.
Public Class Exception The exception that is thrown when errors occur during application execution.
Public Class FlagsAttribute Indicates that an enumeration can be treated as a bit field (a set of flags).
Public Class GC Controls the system garbage collector, a service that automatically reclaims unused computer memory.
Public Class IndexOutOfRangeException The exception that is thrown when an attempt is made to access an object in an array and the index number of that object is outside the bounds of the array.
Public Class InvalidCastException The exception that is thrown whenever invalid casting or explicit conversion occurs.
Public Class InvalidOperationException The exception that is thrown when a method call is invalid for a specified object's current state.
Public Class MarshalByRefObject Provides access to objects across application domain boundaries in applications that support remoting.
Public Class Math A small collection of common mathematical functions.
Public Class MTAThreadAttribute This class is intended for internal use. Indicates that the COM threading model for a specific application is set to multithreaded apartment (MTA).
Public Class MulticastDelegate Represents a multicast delegate, which is a delegate that can contain multiple elements in its invocation list.
Public Class NonSerializedAttribute Indicates that a field of a serializable class should not be serialized.
Public Class NotImplementedException The exception that is thrown when a requested method or operation is not implemented.
Public Class NotSupportedException The exception that is thrown when a called method is not supported by .NET Micro Framework.
Public Class NullReferenceException The exception that is thrown when there is an attempt to dereference a null object reference.
Public Class Object Supports all classes in the .NET Micro Framework class hierarchy and provides low-level services to derived classes. This is the ultimate base class of all classes in the .NET Micro Framework; it is the root of the type hierarchy.
Public Class ObjectDisposedException The exception that is thrown when an operation is performed on a disposed object.
Public Class ObsoleteAttribute Marks the program elements that are no longer in use.
Public Class OutOfMemoryException The exception that is thrown when there is not enough memory available to continue the execution of a program.
Public Class ParamArrayAttribute Indicates that the specified method will accept a variable number of arguments in its invocation.
Public Class Random Generates pseudo-random numbers.
Public Class SerializableAttribute Indicates that a specified class can be serialized.
Public Class STAThreadAttribute Indicates that the COM threading model for a specific application is set to single-threaded apartment (STA).
Public Class String Represents a text string composed of Unicode characters.
Public Class SystemException Constitutes the base class for predefined exceptions in the System namespace.
Public Class TimeZone Represents a specific time zone.
Public Class Type Represents type declarations for the following categories of types: class types, interface types, array types, value types, and enumeration types.
Public Class Uri Provides an object representation of a uniform resource identifier (URI) and easy access to the parts of the URI.
Public Class ValueType Constitutes the base class for value types.
Public Class Version Represents the version number for a common language runtime assembly. This class cannot be inherited.
Public Class WeakReference Represents a weak reference, which references an object but still leaves it prone to garbage collection.


Name Description
Public Interface IAsyncResult Represents the status of an asynchronous operation.
Public Interface ICloneable Supports cloning, which creates a new instance (object) of a specific class such that the new object is a copy of an existing object of that class.
Public Interface IComparable Defines a generalized comparison method that a value type or class implements to create a type-specific comparison method.
Public Interface ICustomFormatter Defines a method that supports custom, user-defined formatting of a specified object's value.
Public Interface IDisposable Defines a method that frees, releases, or resets allocated unmanaged resources.
Public Interface IFormatProvider Provides a mechanism for retrieving an object to control formatting.
Public Interface IFormattable Provides functionality for formatting the value of an object as a string representation.


Name Description
Public Structure Boolean Represents a Boolean value.
Public Structure Byte Represents a 8-bit unsigned integer.
Public Structure Char Represents a Unicode character.
Public Structure DateTime Represents a specific instant in time, expressed as a date and a time of day.
Public Structure Double Represents a double-precision floating point number.
Public Structure Guid Represents a globally unique identifier (GUID).
Public Structure Int16 Represents a 16-bit integer.
Public Structure Int32 Represents a 32-bit integer.
Public Structure Int64 Represents a 64-bit integer.
Public Structure IntPtr A platform-specific type that is used to represent a pointer or a handle.
Public Structure RuntimeArgumentHandle References a variable-length argument list.
Public Structure RuntimeFieldHandle Provides a field descriptor for internal use by the common language runtime (CLR).
Public Structure RuntimeMethodHandle RuntimeMethodHandle is a handle to the internal metadata representation of a method.
Public Structure RuntimeTypeHandle Represents a type using an internal metadata token.
Public Structure SByte Represents an 8-bit signed integer.
Public Structure Single Represents a single-precision floating point number.
Public Structure TimeSpan Specifies a discrete period of time, or a time span.
Public Structure TypedReference Describes objects that contain both a managed pointer to a location and a runtime representation of the type that may be stored at that location.
Public Structure UInt16 Represents a 16-bit unsigned integer.
Public Structure UInt32 Represents a 32-bit unsigned integer.
Public Structure UInt64 Represents a 64-bit unsigned integer.
Public Structure UIntPtr A platform-specific type that is used to represent a pointer or a handle.
Public Structure Void Specifies a return value for a method that does not return a value.


Name Description
Public Delegate AsyncCallback References the callback method to be invoked when an asynchronous operation is completed.


Name Description
Public Enumeration AttributeTargets Contains the application elements on which it is valid to apply an attribute.
Public Enumeration DateTimeKind Specifies whether a DateTime object represents a local time, a Coordinated Universal Time (UTC), or is not specified as either local time or UTC.
Public Enumeration DayOfWeek Contains values you can use to specify the day of the week.
Public Enumeration TypeCode Contains values that specify the type of an object.
Public Enumeration Uri.Flags Defines flags that are stored in the m_Flags field of the Uri class.
Public Enumeration UriHostNameType Defines host name types for the http and https protocols.
Public Enumeration UriKind Defines the kinds of Uris, for methods of Uri such as IsWellFormedUriString.


Note that unlike the .NET Framework for desktop computers, the Visual Studio application wizard for the .NET Micro Framework does not automatically add a reference to the file System.dll, which contains the System namespace. This is by design. You must manually add a reference to System.dll to your Visual Studio project to be able to access items in the System namespace.