System Namespace

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System Namespace

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The System namespace contains the following members:

• Classes
• Interfaces
• Structures
• Delegates
• Enumerations

These members define commonly used value and reference data types, events and event handlers, interfaces, attributes, and exceptions. These members also provide services supporting data type conversion, method parameter manipulation, remote application invocation, local application invocation, application environment management, and supervision of managed and unmanaged applications.

Classes

Name	Description
AccessViolationException	It is used to throw an exception when there is an attempt to read or write protected memory.
ActivationContext	It is used to identify the activation context for a current application.
Activator	It is used to contain methods to create types of objects locally or remotely, or obtain references to existing remote objects.
AppDomain	It is used to represent an application domain, which is an isolated environment where applications execute.
AppDomainManager	It is used to provide a managed equivalent of an unmanaged host.
AppDomainSetup	It is used to represent assembly binding information that can be added to an instance of AppDomain.
AppDomainUnloadedException	It is used to throw an exception when an attempt is made to access an unloaded application domain.
ApplicationException	It is used to throw an exception when a non-fatal application error occurs.
ApplicationId	It is used to contain information used to uniquely identify an application.
ApplicationIdentity	It is used to provide the ability to uniquely identify a manifest-activated application.
ArgumentException	It is used to throw an exception when one of the arguments provided to a method is not valid.
ArgumentNullException	It is used to throw an exception when a null reference is passed to a method that does not accept it as a valid argument.
ArgumentOutOfRangeException	It is used to throw an exception when the value of an argument is outside the allowable range of values as defined by the invoked method.
ArithmeticException	It is used to throw an exception for errors in an arithmetic, casting, or conversion operation.
Array	It is used to provide methods for creating, manipulating, searching, and sorting arrays.
ArrayTypeMismatchException	It is used to throw an exception when an attempt is made to store an element of the wrong type within an array.
AssemblyLoadEventArgs	It is used to provide data for the AssemblyLoad event.
Attribute	It is used to represent the base class for custom attributes.
AttributeUsageAttribute	It is used to specify the usage of another attribute class.
BadImageFormatException	It is used to throw an exception when the file image of a DLL or an executable program is invalid.
BitConverter	It is used to convert base data types to an array of bytes, and an array of bytes to base data types.
Buffer	It is used to manipulate arrays of primitive types.
CannotUnloadAppDomainException	It is used to throw an exception when an attempt to unload an application domain fails.
CharEnumerator	It is used to support iterating over a String object and reading its individual characters.
CLSCompliantAttribute	It is used to indicate whether a program element is compliant with the Common Language Specification (CLS).
Console	It is used to represent the standard input, output, and error streams for console applications.
ConsoleCancelEventArgs	It is used to provide data for the Console.CancelKeyPress event.
ContextBoundObject	It is used to define the base class for all context-bound classes.
ContextMarshalException	It is used to throw an exception when an attempt to marshal an object across a context boundary fails.
ContextStaticAttribute	It is used to indicate that the value of a static field is unique for a particular context.
Convert	It is used to convert a base data type to another base data type.
DataMisalignedException	It is used to throw an exception when a unit of data is read from or written to an address that is not a multiple of the data size.
DBNull	It is used to represent a null value.
Delegate	It is used to represent 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.
DivideByZeroException	It is used to throw an exception when there is an attempt to divide an integral or decimal value by zero.
DllNotFoundException	It is used to throw an exception when a DLL specified in a DLL import cannot be found.
DuplicateWaitObjectException	It is used to throw an exception when an object appears more than once in an array of synchronization objects.
EntryPointNotFoundException	It is used to throw an exception when an attempt to load a class fails due to the absence of an entry method.
Environment	It is used to provide information about, and means to manipulate, the current environment and platform.
EventArgs	It is the base class for classes containing event data.
Exception	It is used to represent errors that occur during application execution.
ExecutionEngineException	It is used to throw an exception when there is an internal error in the execution engine of the common language runtime.
FieldAccessException	It is used to throw an exception when there is an invalid attempt to access a private or protected field inside a class.
FileStyleUriParser	It is a customizable parser based on the File scheme.
FlagsAttribute	It is used to indicate that an enumeration can be treated as a bit field.
FormatException	It is used to throw an exception when the format of an argument does not meet the parameter specifications of the invoked method.
FtpStyleUriParser	It is a customizable parser based on the File Transfer Protocol (FTP) scheme.
GC	It is used to control the system garbage collector, a service that automatically reclaims unused memory.
GenericUriParser	It is a customizable parser for a hierarchical URI.
GopherStyleUriParser	It is a customizable parser based on the Gopher scheme.
HttpStyleUriParser	It is a customizable parser based on the HTTP scheme.
IndexOutOfRangeException	It is used to throw an exception when an attempt is made to access an element of an array with an index that is outside the bounds of the array.
InsufficientMemoryException	It is used to throw an exception when a check for sufficient available memory fails.
InvalidCastException	It is used to throw an exception for invalid casting or explicit conversion.
InvalidOperationException	It is used to throw an exception when a method call is invalid for an object's current state.
InvalidProgramException	It is used to throw an exception when an application contains invalid Microsoft intermediate language (MSIL) or metadata.
LdapStyleUriParser	It is a customizable parser based on the Lightweight Directory Access Protocol (LDAP) scheme.
LoaderOptimizationAttribute	It is used to set the default loader optimization policy for the main method of an executable application.
LocalDataStoreSlot	It is used to encapsulate a memory slot to store local data.
MarshalByRefObject	It is used to enable access to objects across application domain boundaries in applications that support remoting.
Math	It is used to provide constants and static methods for trigonometric, logarithmic, and other common mathematical functions.
MemberAccessException	It is used to throw an exception when an attempt to access a class member fails.
MethodAccessException	It is used to throw an exception when there is an invalid attempt to access a private or protected method inside a class.
MissingFieldException	It is used to throw an exception when there is an attempt to dynamically access a field that does not exist.
MissingMemberException	It is used to throw an exception when there is an attempt to dynamically access a class member that does not exist.
MissingMethodException	It is used to throw an exception when there is an attempt to dynamically access a method that is not available.
MTAThreadAttribute	It is used to indicate that a COM threading model for an application is multithreaded apartment (MTA).
MulticastDelegate	It is used to represent a multicast delegate.
MulticastNotSupportedException	It is used to throw an exception when there is an attempt to combine two instances of a non-combinable delegate type unless one of the operands is a null reference.
NetPipeStyleUriParser	It is a parser based on the NetPipe scheme for the "Indigo" system.
NetTcpStyleUriParser	It is a parser based on the NetTcp scheme for the "Indigo" system.
NewsStyleUriParser	It is a customizable parser based on the news scheme using the Network News Transfer Protocol (NNTP).
NonSerializedAttribute	It is used to indicate that a field of a serializable class should not be serialized.
NotFiniteNumberException	It is used to throw an exception when a floating-point value is positive infinity, negative infinity, or Not-a-Number (NaN).
NotImplementedException	It is used to throw an exception when a requested method or operation is not implemented.
NotSupportedException	It is used to throw an exception when an invoked method is not supported, or when there is an attempt to read, search, or write to a stream that does not support the invoked functionality.
Nullable	It is used to support a value type that can be assigned a null reference.
NullReferenceException	It is used to throw an exception when there is an attempt to de-reference a null object reference.
Object	It is used to support all classes in the .NET Framework class hierarchy and provides low-level services to derived classes.
ObjectDisposedException	It is used to throw an exception when an operation is performed on a disposed object.
ObsoleteAttribute	It is used to mark an application elements that are no longer in use.
OperatingSystem	It is used to represent information about an operating system, such as the version and platform identifier.
OperationCanceledException	It is used to throw an exception in a thread on cancellation of an operation that the thread was executing.
OutOfMemoryException	It is used to throw an exception when there is not enough memory to continue the execution of an application.
OverflowException	It is used to throw an exception when an arithmetic, casting, or conversion operation in a checked context results in an overflow.
ParamArrayAttribute	It is used to indicate that the method will allow a variable number of arguments in its invocation.
PlatformNotSupportedException	It is used to throw an exception when a feature does not run on a particular platform.
Random	It is used to represent a pseudo-random number generator.
RankException	It is used to throw an exception when an array with the wrong number of dimensions is passed to a method.
ResolveEventArgs	It is used to provide data for the TypeResolve, ResourceResolve, and AssemblyResolve events.
SerializableAttribute	It is used to indicate that a class can be serialized.
StackOverflowException	It is used to throw an exception when the execution stack overflow occurs by having too many pending method calls.
STAThreadAttribute	It is used to indicate that a COM threading model for an application is single-threaded apartment (STA).
String	It is used to represent text as a series of Unicode characters.
StringComparer	It is used to represent a string comparison operation that uses specific case and culture-based or ordinal comparison rules.
SystemException	It is used to define the base class for predefined exceptions in the System namespace.
ThreadStaticAttribute	It is used to indicate that the value of a static field is unique for each thread.
TimeoutException	It is used to throw an exception when the time allotted for a process or operation has expired.
TimeZone	It is used to represent a time zone.
Type	It is used to represent type declarations: class types, value types, interface types, array types, enumeration types, type parameters, generic type definitions, and open or closed constructed generic types.
TypeInitializationException	It is used to throw an exception as a wrapper around the exception thrown by the class initializer.
TypeLoadException	It is used to throw an exception when type loading failures occur.
TypeUnloadedException	It is used to throw an exception when there is an attempt to access an unloaded class.
UnauthorizedAccessException	It is used to throw an exception when the operating system denies access because of an input-output (IO) error or a specific type of security error.
UnhandledExceptionEventArgs	It is used to provide data for the event that is raised when there is an exception that is not handled by any application domain.
Uri	It is used to provide an object representation of a Uniform Resource Identifier (URI) and easy access to the parts of the URI.
UriFormatException	It is used to throw an exception when an invalid Uniform Resource Identifier (URI) is detected.
UriParser	It is used to parse a new URI scheme.
UriTypeConverter	It is used to convert a String type to a Uri type and vice versa.
ValueType	It is used to provide the base class for value types.
Version	It is used to represent the version number for a common language runtime (CLR) assembly.
WeakReference	It is used to represent a weak reference, while still allowing that object to be garbage collected.

Interfaces

Name	Description
_AppDomain	It is used to provide the public members of the System.AppDomain class to unmanaged code.
IAppDomainSetup	It is used to represent assembly binding information that can be added to an instance of AppDomain.
IAsyncResult	It is used to represent the status of an asynchronous operation.
ICloneable	It is used to support cloning, which creates a new instance of a class with the same value as an existing instance.
IComparable	It is used to define a generalized comparison method that a value type or class implements to create a type-specific comparison method.
IConvertible	It is used to define methods that convert the value of an implementing reference or value type to a common language runtime type.
ICustomFormatter	It is used to define a method that supports custom, user defined formatting of the value of an object.
IDisposable	It is used to define a method to release allocated unmanaged resources.
IEquatable	It is used to define a generalized method that a value type or class implements to create a type specific method for determining equality of instances.
IFormatProvider	It is used to provide a mechanism for retrieving an object to control formatting.
IFormattable	It is used to provide functionality to format the value of an object into a string representation.
IServiceProvider	It is used to define a mechanism for retrieving a service object.

Structures

Name	Description
ArgIterator	It is used to represent a variable-length argument list.
ArraySegment	It is used to delimit a section of a one-dimensional array.
Boolean	It is used to represent a Boolean value.
Byte	It is used to represent an 8-bit unsigned integer.
Char	It is used to represent a Unicode character.
ConsoleKeyInfo	It is used to describe the console key that was pressed, including the character represented by the console key and the state of the SHIFT, ALT, and CTRL modifier keys.
DateTime	It is used to represent an instant in time, expressed as a date and time of day.
Decimal	It is used to represent a decimal number.
Double	It is used to represent a double-precision floating point number.
Enum	It is used to provide the base class for enumerations.
Guid	It is used to represent a globally unique identifier (GUID).
Int16	It is used to represent a 16-bit signed integer.
Int32	It is used to represent a 32-bit signed integer.
Int64	It is used to represent a 64-bit signed integer.
IntPtr	It is used to represent a pointer or a handle.
ModuleHandle	It is used to represent a runtime handle for a module.
Nullable	It is used to represent an object whose underlying type is a value type that can also be assigned a null reference like a reference type.
RuntimeArgumentHandle	It is used to reference a variable-length argument list.
RuntimeFieldHandle	It is used to represent a field using an internal metadata token.
RuntimeMethodHandle	It is a handle to the internal metadata representation of a method.
RuntimeTypeHandle	It is used to represent a type using an internal metadata token.
SByte	It is used to represent an 8-bit signed integer.
Single	It is used to represent a single-precision floating point number.
TimeSpan	It is used to represent a time interval.
TypedReference	It is used to describe objects that contain both a managed pointer to a location and a runtime representation of a type.
UInt16	It is used to represent a 16-bit unsigned integer.
UInt32	It is used to represent a 32-bit unsigned integer.
UInt64	It is used to represent a 64-bit unsigned integer.
UIntPtr	It is a platform specific type that is used to represent a pointer or a handle.
Void	It is used to specify a return value type for a method that does not return a value.

Delegates

Name	Description
Action	It is used to represent the method that performs an action on the specified object.
AppDomainInitializer	It is used to represent the callback method to invoke when an application domain is initialized.
AssemblyLoadEventHandler	It is used to represent the method that handles the AssemblyLoad event of an AppDomain.
AsyncCallback	It is used to reference the callback method to be called when the asynchronous operation is completed.
Comparison	It is used to represent the method that compares two objects of the same type.
ConsoleCancelEventHandler	It is used to represent the method that will handle the CancelKeyPress event of a System.Console.
Converter	It is used to represent a method that converts an object from one type to another type.
CrossAppDomainDelegate	It is used by DoCallBack for cross-application domain calls.
EventHandler	It is used to represent the method that will handle an event that has no event data.
Predicate	It is used to represent the method that defines a set of criteria and determines whether the specified object meets those criteria.
ResolveEventHandler	It is used to represent the method that handles the TypeResolve, ResourceResolve, and AssemblyResolve events of an AppDomain.
UnhandledExceptionEventHandler	It is used to represent the method that will handle the event raised by an exception, which is not handled by the application domain.

Enumerations

Name	Description
ActivationContext.ContextForm	It is used to indicate a context for a manifest activated application.
AppDomainManagerInitializationOptions	It is used to specify the action that a custom application domain manager takes when initializing a new domain.
AttributeTargets	It is used to specify an application elements on which it is valid to apply an attribute.
Base64FormattingOptions	It is used to specify whether System.Convert.ToBase64CharArray and System.Convert.ToBase64String methods insert line breaks in their output.
ConsoleColor	It is used to specify constants that define foreground and background colors for the console.
ConsoleKey	It is used to specify the standard keys on a console.
ConsoleModifiers	It is used to represent the SHIFT, ALT, and CTRL modifier keys on a keyboard.
ConsoleSpecialKey	It is used to specify combinations of modifier and console keys that can interrupt a current process.
DateTimeKind	It is used to specify whether a DateTime object represents a local time, a Coordinated Universal Time (UTC), or is not specified.
DayOfWeek	It is used to specify a day of the week.
Environment.SpecialFolder	It is used to specify enumerated constants used to retrieve directory paths to system's special folders.
EnvironmentVariableTarget	It is used to specify the location where an environment variable is stored or retrieved in a set or get operation.
GenericUriParserOptions	It is used to specify options for a UriParser.
LoaderOptimization	It is used with the LoaderOptimizationAttribute class to specify loader optimizations for an executable.
MidpointRounding	It is used to specify how mathematical rounding methods should process a number that is midway between the two numbers.
PlatformID	It is used to identify the operating system, or platform, supported by an assembly.
StringComparison	It is used to specify the culture, case, and sort rules to be used by the overloaded String.Compare and String.Equals methods.
StringSplitOptions	It is used to specify whether the overloaded System.String.Split method include or omit empty substrings from the return value.
TypeCode	It is used to specify the type of an object.
UriComponents	It is used to specify the parts of a Uri.
UriFormat	It is used to control how URI information is escaped.
UriHostNameType	It is used to define host name types for the Uri.CheckHostName method.
UriKind	It is used to define the kinds of Uris for the Uri.IsWellFormedUriString and several System.Uri methods.
UriPartial	It is used to define the parts of a URI for the Uri.GetLeftPart method.

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