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System Namespace
.NET Framework 1.1
The System namespace contains fundamental classes and base classes that define commonly-used value and reference data types, events and event handlers, interfaces, attributes, and processing exceptions.
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.
Classes
| Class | Description |
|---|---|
| Activator | Contains methods to create types of objects locally or remotely, or obtain references to existing remote objects. |
| AppDomain | Represents an application domain, which is an isolated environment where applications execute. This class cannot be inherited. |
| 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 | The exception that is thrown when a non-fatal application error occurs. |
| 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 | 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 DLL or an executable program is invalid. |
| 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 and reading its individual characters. |
| 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. |
| 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. |
| DBNull | Represents a null value. |
| 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 | EventArgs is the base class for classes containing 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. |
| FieldAccessException | The exception that is thrown when there is an invalid attempt to access a private or protected field inside a class. |
| 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 does not meet the parameter specifications of the invoked method. |
| GC | Controls the system garbage collector, a service that automatically reclaims unused memory. |
| IndexOutOfRangeException | The exception that is thrown when an attempt is made to access an element of an array with an index that is outside the bounds of the array. 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. |
| 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. |
| MemberAccessException | The exception that is thrown when an attempt to access a class member fails. |
| MethodAccessException | The exception that is thrown when there is an invalid attempt to access a private or protected method inside a class. |
| MissingFieldException | The exception that is thrown when there is an attempt to dynamically access a field that does not exist. |
| MissingMemberException | The exception that is thrown when there is an attempt to dynamically access a class member that does not exist. |
| 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 instances of a non-combinable delegate type unless one of the operands is a null reference (Nothing in Visual Basic). This class cannot be inherited. |
| 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. |
| NullReferenceException | The exception that is thrown when there is an attempt to dereference a null object reference. |
| Object | Supports all classes in the .NET Framework class hierarchy and provides low-level services to derived classes. This is the ultimate base class of all classes in the .NET Framework; 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 the program elements that are no longer in use. This class cannot be inherited. |
| OperatingSystem | Represents information about an operating system, such as the version and platform identifier. |
| 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 the 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. |
| Random | Represents a pseudo-random number generator, a device 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 the TypeResolve, ResourceResolve, and AssemblyResolve events. |
| SerializableAttribute | Indicates that a class can be serialized. This class cannot be inherited. |
| StackOverflowException | The exception that is thrown when the execution stack overflows by having too many pending method calls. This class cannot be inherited. |
| STAThreadAttribute | Indicates that the COM threading model for an application is single-threaded apartment (STA). |
| String | Represents text; that is, a series of Unicode characters. |
| SystemException | Defines the base class for predefined exceptions in the System namespace. |
| ThreadStaticAttribute | Indicates that the value of a static field is unique for each thread. |
| TimeZone | Represents a time zone. |
| Type | Represents type declarations: class types, interface types, array types, value types, and enumeration types. |
| 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 by the 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 indentifiers (URIs) and modifies URIs for the Uri class. |
| UriFormatException | The exception that is thrown when an invalid Uniform Resource Identifier (URI) is detected. |
| ValueType | Provides the base class for value types. |
| Version | Represents the version number for a common language runtime assembly. This class cannot be inherited. |
| WeakReference | Represents a weak reference, which references an object while still allowing it to be garbage collected. |
Interfaces
| Interface | Description |
|---|---|
| IAppDomainSetup | Represents assembly binding information that can be added to an instance of AppDomain. |
| 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 comparison method that a value type or class implements to create a type-specific comparison method. |
| 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, user-defined formatting of the value of an object. |
| IDisposable | Defines a method to release allocated unmanaged resources. |
| 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. |
| IServiceProvider | Defines a mechanism for retrieving a service object; that is, an object that provides custom support to other objects. |
| _AppDomain | Represents an application domain, which is an isolated environment where applications execute. |
Structures
| Structure | Description |
|---|---|
| ArgIterator | Represents a variable-length argument list; that is, the parameters of a function that takes a variable number of arguments. |
| Boolean | Represents a Boolean value. |
| Byte | Represents an 8-bit unsigned integer. |
| Char | Represents a Unicode character. |
| DateTime | Represents an instant in time, typically expressed as a date and time of day. |
| Decimal | Represents a decimal number. |
| Double | Represents a double-precision floating point number. |
| Guid | Represents a globally unique identifier (GUID). |
| Int16 | Represents a 16-bit signed integer. |
| Int32 | Represents a 32-bit signed integer. |
| Int64 | Represents a 64-bit signed integer. |
| IntPtr | A platform-specific type that is used to represent a pointer or a handle. |
| RuntimeArgumentHandle | References a variable-length argument list. |
| RuntimeFieldHandle | Represents a field using an internal metadata token. |
| RuntimeMethodHandle | The 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. |
| Single | Represents a single-precision floating point number. |
| TimeSpan | Represents a time interval. |
| 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. |
| UInt16 | Represents a 16-bit unsigned integer. |
| UInt32 | Represents a 32-bit unsigned integer. |
| UInt64 | Represents a 64-bit unsigned integer. |
| UIntPtr | A platform-specific type that is used to represent a pointer or a handle. |
| Void | Indicates a method that does not return a value; that is, the method has the void return type. |
Delegates
| Delegate | Description |
|---|---|
| AssemblyLoadEventHandler | Represents the method that handles the AssemblyLoad event of an AppDomain. |
| AsyncCallback | References the callback method to be called when the asynchronous operation is completed. |
| CrossAppDomainDelegate | Used by DoCallBack for cross-application domain calls. |
| EventHandler | Represents the method that will handle the event that has no event data. |
| ResolveEventHandler | Represents the method that handles the TypeResolve, ResourceResolve, and AssemblyResolve events of an AppDomain. |
| UnhandledExceptionEventHandler | Represents the method that will handle the event raised by an exception that is not handled by the application domain. |
Enumerations
| Enumeration | Description |
|---|---|
| AttributeTargets | Specifies the application elements on which it is valid to apply an attribute. |
| DayOfWeek | Specifies the day of the week. |
| Environment.SpecialFolder | Specifies enumerated constants used to retrieve directory paths to system special folders. |
| LoaderOptimization | An enumeration used with the LoaderOptimizationAttribute class to specify loader optimizations for an executable. |
| PlatformID | Describes the platforms supported by an assembly. |
| TypeCode | Specifies the type of an object. |
| UriHostNameType | Defines host name types for the Uri.CheckHostName method. |
| UriPartial | Defines the parts of a URI for the Uri.GetLeftPart method. |
See Also
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