System Namespace (original) (raw)

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

Classes

Name	Description
AccessViolationException	The exception that is thrown when there is an attempt to read or write protected memory.
ActivationContext	Identifies the activation context for the current application. This class cannot be inherited.
Activator	Contains methods to create types of objects locally or remotely, or obtain references to existing remote objects. This class cannot be inherited.
AggregateException	Represents one or more errors that occur during application execution.
AppContext	Provides members for setting and retrieving data about an application's context.
AppDomain	Represents an application domain, which is an isolated environment where applications execute. This class cannot be inherited.
AppDomainManager	Provides a managed equivalent of an unmanaged host.
AppDomainSetup	Represents assembly binding information that can be added to an instance of AppDomain.
AppDomainUnloadedException	The exception that is thrown when an attempt is made to access an unloaded application domain.
ApplicationException	Serves as the base class for application-defined exceptions.
ApplicationId	Contains information used to uniquely identify a manifest-based application. This class cannot be inherited.
ApplicationIdentity	Provides the ability to uniquely identify a manifest-activated application. This class cannot be inherited.
ArgumentException	The exception that is thrown when one of the arguments provided to a method is not valid.
ArgumentNullException	The exception that is thrown when a null reference (Nothing in Visual Basic) is passed to a method that does not accept it as a valid argument.
ArgumentOutOfRangeException	The exception that is thrown when the value of an argument is outside the allowable range of values as defined by the invoked method.
ArithmeticException	The exception that is thrown for errors in an arithmetic, casting, or conversion operation.
Array	Provides methods for creating, manipulating, searching, and sorting arrays, thereby serving as the base class for all arrays in the common language runtime.
ArrayTypeMismatchException	The exception that is thrown when an attempt is made to store an element of the wrong type within an array.
AssemblyLoadEventArgs	Provides data for the AssemblyLoad event.
Attribute	Represents the base class for custom attributes.
AttributeUsageAttribute	Specifies the usage of another attribute class. This class cannot be inherited.
BadImageFormatException	The exception that is thrown when the file image of a dynamic link library (DLL) or an executable program is invalid.
BinaryData	A lightweight abstraction for a payload of bytes that supports converting between string, stream, JSON, and bytes.
BitConverter	Converts base data types to an array of bytes, and an array of bytes to base data types.
Buffer	Manipulates arrays of primitive types.
CannotUnloadAppDomainException	The exception that is thrown when an attempt to unload an application domain fails.
CharEnumerator	Supports iterating over a String object and reading its individual characters. This class cannot be inherited.
CLSCompliantAttribute	Indicates whether a program element is compliant with the Common Language Specification (CLS). This class cannot be inherited.
Console	Represents the standard input, output, and error streams for console applications. This class cannot be inherited.
ConsoleCancelEventArgs	Provides data for the CancelKeyPress event. This class cannot be inherited.
ContextBoundObject	Defines the base class for all context-bound classes.
ContextMarshalException	The exception that is thrown when an attempt to marshal an object across a context boundary fails.
ContextStaticAttribute	Indicates that the value of a static field is unique for a particular context.
Convert	Converts a base data type to another base data type.
DataMisalignedException	The exception that is thrown when a unit of data is read from or written to an address that is not a multiple of the data size. This class cannot be inherited.
DBNull	Represents a nonexistent value. This class cannot be inherited.
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.
DivideByZeroException	The exception that is thrown when there is an attempt to divide an integral or Decimal value by zero.
DllNotFoundException	The exception that is thrown when a DLL specified in a DLL import cannot be found.
DuplicateWaitObjectException	The exception that is thrown when an object appears more than once in an array of synchronization objects.
EntryPointNotFoundException	The exception that is thrown when an attempt to load a class fails due to the absence of an entry method.
Enum	Provides the base class for enumerations.
Environment	Provides information about, and means to manipulate, the current environment and platform. This class cannot be inherited.
EventArgs	Represents the base class for classes that contain event data, and provides a value to use for events that do not include event data.
Exception	Represents errors that occur during application execution.
ExecutionEngineException	The exception that is thrown when there is an internal error in the execution engine of the common language runtime. This class cannot be inherited.
FakeLoggerServiceProviderExtensions	Extensions for configuring fake logging, used in unit tests.
FakeRedactionServiceProviderExtensions	Extensions that allow registering a fake redactor in the application.
FieldAccessException	The exception that is thrown when there is an invalid attempt to access a private or protected field inside a class.
FileStyleUriParser	A customizable parser based on the File scheme.
FlagsAttribute	Indicates that an enumeration can be treated as a bit field; that is, a set of flags.
FormatException	The exception that is thrown when the format of an argument is invalid, or when a composite format string is not well formed.
FormattableString	Represents a composite format string, along with the arguments to be formatted.
FtpStyleUriParser	A customizable parser based on the File Transfer Protocol (FTP) scheme.
GC	Controls the system garbage collector, a service that automatically reclaims unused memory.
GenericUriParser	A customizable parser for a hierarchical URI.
GopherStyleUriParser	A customizable parser based on the Gopher scheme.
HttpStyleUriParser	A customizable parser based on the HTTP scheme.
IndexOutOfRangeException	The exception that is thrown when an attempt is made to access an element of an array or collection with an index that is outside its bounds.
InsufficientExecutionStackException	The exception that is thrown when there is insufficient execution stack available to allow most methods to execute.
InsufficientMemoryException	The exception that is thrown when a check for sufficient available memory fails. This class cannot be inherited.
InvalidCastException	The exception that is thrown for invalid casting or explicit conversion.
InvalidOperationException	The exception that is thrown when a method call is invalid for the object's current state.
InvalidProgramException	The exception that is thrown when a program contains invalid Microsoft intermediate language (MSIL) or metadata. Generally this indicates a bug in the compiler that generated the program. This exception is also thrown when internal runtime implementation limits have been exceeded by the program.
InvalidTimeZoneException	The exception that is thrown when time zone information is invalid.
Lazy	Provides support for lazy initialization.
Lazy<T,TMetadata>	Provides a lazy indirect reference to an object and its associated metadata for use by the Managed Extensibility Framework.
LdapStyleUriParser	A customizable parser based on the Lightweight Directory Access Protocol (LDAP) scheme.
LoaderOptimizationAttribute	Used to set the default loader optimization policy for the main method of an executable application.
LocalDataStoreSlot	Encapsulates a memory slot to store local data. This class cannot be inherited.
MarshalByRefObject	Enables access to objects across application domain boundaries in applications that support remoting.
Math	Provides constants and static methods for trigonometric, logarithmic, and other common mathematical functions.
MathF	Provides constants and static methods for trigonometric, logarithmic, and other common mathematical functions.
MemberAccessException	The exception that is thrown when an attempt to access a class member fails.
MemoryExtensions	Provides extension methods for the memory-related and span-related types, such as Memory, ReadOnlyMemory, Span, and ReadOnlySpan.
MethodAccessException	The exception that is thrown when there is an invalid attempt to access a method, such as accessing a private method from partially trusted code.
MissingFieldException	The exception that is thrown when there is an attempt to dynamically access a field that does not exist. If a field in a class library has been removed or renamed, recompile any assemblies that reference that library.
MissingMemberException	The exception that is thrown when there is an attempt to dynamically access a class member that does not exist or that is not declared as public. If a member in a class library has been removed or renamed, recompile any assemblies that reference that library.
MissingMethodException	The exception that is thrown when there is an attempt to dynamically access a method that does not exist.
MTAThreadAttribute	Indicates that the COM threading model for an application is multithreaded apartment (MTA).
MulticastDelegate	Represents a multicast delegate; that is, a delegate that can have more than one element in its invocation list.
MulticastNotSupportedException	The exception that is thrown when there is an attempt to combine two delegates based on the Delegate type instead of the MulticastDelegate type. This class cannot be inherited.
NetPipeStyleUriParser	A parser based on the NetPipe scheme for the "Indigo" system.
NetTcpStyleUriParser	A parser based on the NetTcp scheme for the "Indigo" system.
NewsStyleUriParser	A customizable parser based on the news scheme using the Network News Transfer Protocol (NNTP).
NonSerializedAttribute	Indicates that a field of a serializable class should not be serialized. This class cannot be inherited.
NotFiniteNumberException	The exception that is thrown when a floating-point value is positive infinity, negative infinity, or Not-a-Number (NaN).
NotImplementedException	The exception that is thrown when a requested method or operation is not implemented.
NotSupportedException	The exception that is thrown when an invoked method is not supported, or when there is an attempt to read, seek, or write to a stream that does not support the invoked functionality.
Nullable	Supports a value type that can be assigned null. This class cannot be inherited.
NullReferenceException	The exception that is thrown when there is an attempt to dereference a null object reference.
Object	Supports all classes in the .NET class hierarchy and provides low-level services to derived classes. This is the ultimate base class of all .NET classes; it is the root of the type hierarchy.
ObjectDisposedException	The exception that is thrown when an operation is performed on a disposed object.
ObsoleteAttribute	Marks program elements that are no longer in use.
OperatingSystem	Represents information about an operating system, such as the version and platform identifier. This class cannot be inherited.
OperationCanceledException	The exception that is thrown in a thread upon cancellation of an operation that the thread was executing.
OutOfMemoryException	The exception that is thrown when there is not enough memory to continue the execution of a program.
OverflowException	The exception that is thrown when an arithmetic, casting, or conversion operation in a checked context results in an overflow.
ParamArrayAttribute	Indicates that a method will allow a variable number of arguments in its invocation. This class cannot be inherited.
PlatformNotSupportedException	The exception that is thrown when a feature does not run on a particular platform.
Progress	Provides an IProgress that invokes callbacks for each reported progress value.
Random	Represents a pseudo-random number generator, which is an algorithm that produces a sequence of numbers that meet certain statistical requirements for randomness.
RankException	The exception that is thrown when an array with the wrong number of dimensions is passed to a method.
ResolveEventArgs	Provides data for loader resolution events, such as the TypeResolve, ResourceResolve, ReflectionOnlyAssemblyResolve, and AssemblyResolve events.
SerializableAttribute	Indicates that a class can be serialized using binary or XML serialization. This class cannot be inherited.
StackOverflowException	The exception that is thrown when the execution stack exceeds the stack size. This class cannot be inherited.
STAThreadAttribute	Indicates that the COM threading model for an application is single-threaded apartment (STA).
String	Represents text as a sequence of UTF-16 code units.
StringComparer	Represents a string comparison operation that uses specific case and culture-based or ordinal comparison rules.
StringNormalizationExtensions	Provides extension methods to work with string normalization.
SystemException	Serves as the base class for system exceptions namespace.
ThreadStaticAttribute	Indicates that the value of a static field is unique for each thread.
TimeoutException	The exception that is thrown when the time allotted for a process or operation has expired.
TimeProvider	Provides an abstraction for time.
TimeZone	Represents a time zone.
TimeZoneInfo	Represents any time zone in the world.
TimeZoneInfo.AdjustmentRule	Provides information about a time zone adjustment, such as the transition to and from daylight saving time.
TimeZoneNotFoundException	The exception that is thrown when a time zone cannot be found.
Tuple	Provides static methods for creating tuple objects.
Tuple	Represents a 1-tuple, or singleton.
Tuple<T1,T2>	Represents a 2-tuple, or pair.
Tuple<T1,T2,T3>	Represents a 3-tuple, or triple.
Tuple<T1,T2,T3,T4>	Represents a 4-tuple, or quadruple.
Tuple<T1,T2,T3,T4,T5>	Represents a 5-tuple, or quintuple.
Tuple<T1,T2,T3,T4,T5,T6>	Represents a 6-tuple, or sextuple.
Tuple<T1,T2,T3,T4,T5,T6,T7>	Represents a 7-tuple, or septuple.
Tuple<T1,T2,T3,T4,T5,T6,T7,TRest>	Represents an _n_-tuple, where n is 8 or greater.
TupleExtensions	Provides extension methods for tuples to interoperate with language support for tuples in C#.
Type	Represents type declarations: class types, interface types, array types, value types, enumeration types, type parameters, generic type definitions, and open or closed constructed generic types.
TypeAccessException	The exception that is thrown when a method attempts to use a type that it does not have access to.
TypeInitializationException	The exception that is thrown as a wrapper around the exception thrown by the class initializer. This class cannot be inherited.
TypeLoadException	The exception that is thrown when type-loading failures occur.
TypeUnloadedException	The exception that is thrown when there is an attempt to access an unloaded class.
UnauthorizedAccessException	The exception that is thrown when the operating system denies access because of an I/O error or a specific type of security error.
UnhandledExceptionEventArgs	Provides data for the event that is raised when there is an exception that is not handled in any application domain.
Uri	Provides an object representation of a uniform resource identifier (URI) and easy access to the parts of the URI.
UriBuilder	Provides a custom constructor for uniform resource identifiers (URIs) and modifies URIs for the Uri class.
UriFormatException	The exception that is thrown when an invalid Uniform Resource Identifier (URI) is detected.
UriParser	Parses a new URI scheme. This is an abstract class.
UriTemplate	A class that represents a Uniform Resource Identifier (URI) template.
UriTemplateEquivalenceComparer	A class used to compare UriTemplate instances for structural (instead of reference) equivalence.
UriTemplateMatch	A class that represents the results of a match operation on a UriTemplate instance.
UriTemplateMatchException	Represents an error when matching a Uri to a UriTemplateTable.
UriTemplateTable	A class that represents an associative set of UriTemplate objects.
UriTypeConverter	Converts a String type to a Uri type, and vice versa.
ValueType	Provides the base class for value types.
Version	Represents the version number of an assembly, operating system, or the common language runtime. This class cannot be inherited.
WeakReference	Represents a weak reference, which references an object while still allowing that object to be reclaimed by garbage collection.
WeakReference	Represents a typed weak reference, which references an object while still allowing that object to be reclaimed by garbage collection.
WindowsRuntimeSystemExtensions	Provides extension methods for converting between tasks and Windows Runtime asynchronous actions and operations.

Structs

Name	Description
ArgIterator	Represents a variable-length argument list; that is, the parameters of a function that takes a variable number of arguments.
ArraySegment.Enumerator	Provides an enumerator for the elements of an ArraySegment.
ArraySegment	Delimits a section of a one-dimensional array.
Boolean	Represents a Boolean (true or false) value.
Byte	Represents an 8-bit unsigned integer.
Char	Represents a character as a UTF-16 code unit.
ConsoleKeyInfo	Describes 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.
DateOnly	Represents dates with values ranging from January 1, 0001 Anno Domini (Common Era) through December 31, 9999 A.D. (C.E.) in the Gregorian calendar.
DateTime	Represents an instant in time, typically expressed as a date and time of day.
DateTimeOffset	Represents a point in time, typically expressed as a date and time of day, relative to Coordinated Universal Time (UTC).
Decimal	Represents a decimal floating-point number.
Delegate.InvocationListEnumerator	Provides an enumerator for the invocation list of a delegate.
Double	Represents a double-precision floating-point number.
Environment.ProcessCpuUsage	Represents the CPU usage statistics of a process.
GCGenerationInfo	Represents the size and the fragmenation of a generation on entry and on exit of the GC reported in GCMemoryInfo.
GCMemoryInfo	Provides a set of APIs that can be used to retrieve garbage collection information.
Guid	Represents a globally unique identifier (GUID).
Half	Represents a half-precision floating-point number.
HashCode	Combines the hash code for multiple values into a single hash code.
Index	Represents a type that can be used to index a collection either from the beginning or the end.
Int128	Represents a 128-bit signed integer.
Int16	Represents a 16-bit signed integer.
Int32	Represents a 32-bit signed integer.
Int64	Represents a 64-bit signed integer.
IntPtr	Represents a signed integer where the bit-width is the same as a pointer.
Memory	Represents a contiguous region of memory.
MemoryExtensions.SpanSplitEnumerator	Enables enumerating each split within a ReadOnlySpan that has been divided using one or more separators.
MemoryExtensions.TryWriteInterpolatedStringHandler	Provides a handler used by the language compiler to format interpolated strings into character spans.
ModuleHandle	Represents a runtime handle for a module.
Nullable	Represents a value type that can be assigned null.
Range	Represents a range that has start and end indexes.
ReadOnlyMemory	Represents a contiguous region of memory, similar to ReadOnlySpan. Unlike ReadOnlySpan, it is not a byref-like type.
ReadOnlySpan.Enumerator	Provides an enumerator for the elements of a ReadOnlySpan.
ReadOnlySpan	Provides a type-safe and memory-safe read-only representation of a contiguous region of arbitrary memory.
RuntimeArgumentHandle	References a variable-length argument list.
RuntimeFieldHandle	Represents a field using an internal metadata token.
RuntimeMethodHandle	RuntimeMethodHandle is a handle to the internal metadata representation of a method.
RuntimeTypeHandle	Represents a type using an internal metadata token.
SByte	Represents an 8-bit signed integer.
SequencePosition	Represents a position in a non-contiguous set of memory. Properties of this type should not be interpreted by anything but the type that created it.
Single	Represents a single-precision floating-point number.
Span.Enumerator	Provides an enumerator for the elements of a Span.
Span	Provides a type-safe and memory-safe representation of a contiguous region of arbitrary memory.
TimeOnly	Represents a time of day, as would be read from a clock, within the range 00:00:00 to 23:59:59.9999999.
TimeSpan	Represents a time interval.
TimeZoneInfo.TransitionTime	Provides information about a specific time change, such as the change from daylight saving time to standard time or vice versa, in a particular time zone.
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.
UInt128	Represents a 128-bit unsigned integer.
UInt16	Represents a 16-bit unsigned integer.
UInt32	Represents a 32-bit unsigned integer.
UInt64	Represents a 64-bit unsigned integer.
UIntPtr	Represents an unsigned integer where the bit-width is the same as a pointer.
UriCreationOptions	Provides options that control how a Uri is created and behaves.
ValueTuple	Provides static methods for creating value tuples.
ValueTuple	Represents a value tuple with a single component.
ValueTuple<T1,T2>	Represents a value tuple with 2 components.
ValueTuple<T1,T2,T3>	Represents a value tuple with 3 components.
ValueTuple<T1,T2,T3,T4>	Represents a value tuple with 4 components.
ValueTuple<T1,T2,T3,T4,T5>	Represents a value tuple with 5 components.
ValueTuple<T1,T2,T3,T4,T5,T6>	Represents a value tuple with 6 components.
ValueTuple<T1,T2,T3,T4,T5,T6,T7>	Represents a value tuple with 7 components.
ValueTuple<T1,T2,T3,T4,T5,T6,T7,TRest>	Represents an _n_-value tuple, where n is 8 or greater.
Void	Specifies a return value type for a method that does not return a value.

Interfaces

Name	Description
_AppDomain	Exposes the public members of the AppDomain class to unmanaged code.
IAppDomainSetup	Represents assembly binding information that can be added to an instance of AppDomain.
IAsyncDisposable	Provides a mechanism for releasing unmanaged resources asynchronously.
IAsyncResult	Represents the status of an asynchronous operation.
ICloneable	Supports cloning, which creates a new instance of a class with the same value as an existing instance.
IComparable	Defines a generalized type-specific comparison method that a value type or class implements to order or sort its instances.
IComparable	Defines a generalized comparison method that a value type or class implements to create a type-specific comparison method for ordering or sorting its instances.
IConvertible	Defines methods that convert the value of the implementing reference or value type to a common language runtime type that has an equivalent value.
ICustomFormatter	Defines a method that supports custom formatting of the value of an object.
IDisposable	Provides a mechanism for releasing unmanaged resources.
IEquatable	Defines a generalized method that a value type or class implements to create a type-specific method for determining equality of instances.
IFormatProvider	Provides a mechanism for retrieving an object to control formatting.
IFormattable	Provides functionality to format the value of an object into a string representation.
IObservable	Defines a provider for push-based notification.
IObserver	Provides a mechanism for receiving push-based notifications.
IParsable	Defines a mechanism for parsing a string to a value.
IProgress	Defines a provider for progress updates.
IServiceProvider	Defines a mechanism for retrieving a service object; that is, an object that provides custom support to other objects.
ISpanFormattable	Provides functionality to format the string representation of an object into a span.
ISpanParsable	Defines a mechanism for parsing a span of characters to a value.
IUtf8SpanFormattable	Provides functionality to format the string representation of an object into a span as UTF-8.
IUtf8SpanParsable	Defines a mechanism for parsing a span of UTF-8 characters to a value.

Enums

Name	Description
ActivationContext.ContextForm	Indicates the context for a manifest-activated application.
AppDomainManagerInitializationOptions	Specifies the action that a custom application domain manager takes when initializing a new domain.
AttributeTargets	Specifies the application elements on which it is valid to apply an attribute.
Base64FormattingOptions	Specifies whether relevant ToBase64CharArray and ToBase64String methods insert line breaks in their output.
ConsoleColor	Specifies constants that define foreground and background colors for the console.
ConsoleKey	Specifies the standard keys on a console.
ConsoleModifiers	Represents the SHIFT, ALT, and CTRL modifier keys on a keyboard.
ConsoleSpecialKey	Specifies combinations of modifier and console keys that can interrupt the current process.
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.
DayOfWeek	Specifies the day of the week.
Environment.SpecialFolder	Specifies enumerated Constant Special Item ID List (CSIDL) values used to retrieve directory paths to system special folders.
Environment.SpecialFolderOption	Specifies options to use for getting the path to a special folder.
EnvironmentVariableTarget	Specifies the location where an environment variable is stored or retrieved in a set or get operation.
GCCollectionMode	Specifies the behavior for a forced garbage collection.
GCKind	Specifies the kind of a garbage collection.
GCNotificationStatus	Provides information about the current registration for notification of the next full garbage collection.
GenericUriParserOptions	Specifies options for a UriParser.
LoaderOptimization	An enumeration used with the LoaderOptimizationAttribute class to specify loader optimizations for an executable.
MidpointRounding	Specifies the strategy that mathematical rounding methods should use to round a number.
PlatformID	Identifies the operating system, or platform, supported by an assembly.
StringComparison	Specifies the culture, case, and sort rules to be used by certain overloads of the Compare(String, String) and Equals(Object) methods.
StringSplitOptions	Specifies options for applicable Split method overloads, such as whether to omit empty substrings from the returned array or trim whitespace from substrings.
TypeCode	Specifies the type of an object.
UriComponents	Specifies the parts of a Uri.
UriFormat	Controls how URI information is escaped.
UriHostNameType	Defines host name types for the CheckHostName(String) method.
UriIdnScope	Provides the possible values for the configuration setting of the IdnElement in the System.Configuration namespace.
UriKind	Defines the different kinds of URIs.
UriPartial	Defines the parts of a URI for the GetLeftPart(UriPartial) method.

Delegates

Name	Description
Action	Encapsulates a method that has no parameters and does not return a value.
Action	Encapsulates a method that has a single parameter and does not return a value.
Action<T1,T2>	Encapsulates a method that has two parameters and does not return a value.
Action<T1,T2,T3>	Encapsulates a method that has three parameters and does not return a value.
Action<T1,T2,T3,T4>	Encapsulates a method that has four parameters and does not return a value.
Action<T1,T2,T3,T4,T5>	Encapsulates a method that has five parameters and does not return a value.
Action<T1,T2,T3,T4,T5,T6>	Encapsulates a method that has six parameters and does not return a value.
Action<T1,T2,T3,T4,T5,T6,T7>	Encapsulates a method that has seven parameters and does not return a value.
Action<T1,T2,T3,T4,T5,T6,T7,T8>	Encapsulates a method that has eight parameters and does not return a value.
Action<T1,T2,T3,T4,T5,T6,T7,T8,T9>	Encapsulates a method that has nine parameters and does not return a value.
Action<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10>	Encapsulates a method that has 10 parameters and does not return a value.
Action<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11>	Encapsulates a method that has 11 parameters and does not return a value.
Action<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12>	Encapsulates a method that has 12 parameters and does not return a value.
Action<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13>	Encapsulates a method that has 13 parameters and does not return a value.
Action<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14>	Encapsulates a method that has 14 parameters and does not return a value.
Action<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14,T15>	Encapsulates a method that has 15 parameters and does not return a value.
Action<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14,T15,T16>	Encapsulates a method that has 16 parameters and does not return a value.
AppDomainInitializer	Represents the callback method to invoke when the application domain is initialized.
AssemblyLoadEventHandler	Represents the method that handles the AssemblyLoad event of an AppDomain.
AsyncCallback	References a method to be called when a corresponding asynchronous operation completes.
Comparison	Represents the method that compares two objects of the same type.
ConsoleCancelEventHandler	Represents the method that will handle the CancelKeyPress event of a Console.
Converter<TInput,TOutput>	Represents a method that converts an object from one type to another type.
CrossAppDomainDelegate	Used by DoCallBack(CrossAppDomainDelegate) for cross-application domain calls.
EventHandler	Represents the method that will handle an event that has no event data.
EventHandler	Represents the method that will handle an event when the event provides data.
EventHandler<TSender,TEventArgs>	Represents the method that will handle an event when the event provides data.
Func	Encapsulates a method that has no parameters and returns a value of the type specified by the TResult parameter.
Func<T,TResult>	Encapsulates a method that has one parameter and returns a value of the type specified by the TResult parameter.
Func<T1,T2,TResult>	Encapsulates a method that has two parameters and returns a value of the type specified by the TResult parameter.
Func<T1,T2,T3,TResult>	Encapsulates a method that has three parameters and returns a value of the type specified by the TResult parameter.
Func<T1,T2,T3,T4,TResult>	Encapsulates a method that has four parameters and returns a value of the type specified by the TResult parameter.
Func<T1,T2,T3,T4,T5,TResult>	Encapsulates a method that has five parameters and returns a value of the type specified by the TResult parameter.
Func<T1,T2,T3,T4,T5,T6,TResult>	Encapsulates a method that has six parameters and returns a value of the type specified by the TResult parameter.
Func<T1,T2,T3,T4,T5,T6,T7,TResult>	Encapsulates a method that has seven parameters and returns a value of the type specified by the TResult parameter.
Func<T1,T2,T3,T4,T5,T6,T7,T8,TResult>	Encapsulates a method that has eight parameters and returns a value of the type specified by the TResult parameter.
Func<T1,T2,T3,T4,T5,T6,T7,T8,T9,TResult>	Encapsulates a method that has nine parameters and returns a value of the type specified by the TResult parameter.
Func<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,TResult>	Encapsulates a method that has 10 parameters and returns a value of the type specified by the TResult parameter.
Func<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,TResult>	Encapsulates a method that has 11 parameters and returns a value of the type specified by the TResult parameter.
Func<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,TResult>	Encapsulates a method that has 12 parameters and returns a value of the type specified by the TResult parameter.
Func<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,TResult>	Encapsulates a method that has 13 parameters and returns a value of the type specified by the TResult parameter.
Func<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14,TResult>	Encapsulates a method that has 14 parameters and returns a value of the type specified by the TResult parameter.
Func<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14,T15,TResult>	Encapsulates a method that has 15 parameters and returns a value of the type specified by the TResult parameter.
Func<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14,T15,T16,TResult>	Encapsulates a method that has 16 parameters and returns a value of the type specified by the TResult parameter.
Predicate	Represents the method that defines a set of criteria and determines whether the specified object meets those criteria.
ResolveEventHandler	Represents a method that handles the TypeResolve, ResourceResolve, or AssemblyResolve event of an AppDomain.
UnhandledExceptionEventHandler	Represents the method that will handle the event raised by an exception that is not handled by the application domain.

Other classes provide services supporting data type conversion, method parameter manipulation, mathematics, remote and local program invocation, application environment management, and supervision of managed and unmanaged applications.

To access types in the System namespace from C# code without having to provide fully qualified type names, include the using System; statement at the beginning of your source code file.

To access types in the System namespace from C++/CLI code without having to provide fully qualified type names, include the using namespace System; statement at the beginning of your source code file. In addition, you must compile with the /clr switch.