Using static classes and methods

Not all .NET Framework classes can be created using New-Object. For example, if you try to create a System.Environment or a System.Math object with New-Object, you will get the following error messages:

New-Object System.Environment
New-Object : Constructor not found. Cannot find an appropriate constructor for
type System.Environment.
At line:1 char:11
+ New-Object  <<<< System.Environment
New-Object System.Math
New-Object : Constructor not found. Cannot find an appropriate constructor for
type System.Math.
At line:1 char:11
+ New-Object  <<<< System.Math

These errors occur because there is no way to create a new object from these classes. These classes are reference libraries of methods and properties that don't change state. You don't need to create them, you simply use them. Classes and methods such as these are called static classes because they're not created, destroyed, or changed. To make this clear we will provide examples that use static classes.

Getting environment data with System.Environment

Usually, the first step in working with an object in Windows PowerShell is to use Get-Member to find out what members it contains. With static classes, the process is a little different because the actual class isn't an object.

Referring to the static System.Environment class

You can refer to a static class by surrounding the class name with square brackets. For example, you can refer to System.Environment by typing the name within brackets. Doing so displays some generic type information:

IsPublic IsSerial Name                                     BaseType
-------- -------- ----                                     --------
True     False    Environment                              System.Object


As we mentioned previously, Windows PowerShell automatically prepends 'System.' to type names when you use New-Object. The same thing happens when using a bracketed type name, so you can specify [System.Environment] as [Environment].

The System.Environment class contains general information about the working environment for the current process, which is powershell.exe when working within Windows PowerShell.

If you try to view details of this class by typing [System.Environment] | Get-Member, the object type is reported as being System.RuntimeType , not System.Environment:

[System.Environment] | Get-Member
   TypeName: System.RuntimeType

To view static members with Get-Member, specify the Static parameter:

[System.Environment] | Get-Member -Static
   TypeName: System.Environment

Name                       MemberType Definition
----                       ---------- ----------
Equals                     Method     static System.Boolean Equals(Object ob...
Exit                       Method     static System.Void Exit(Int32 exitCode)
CommandLine                Property   static System.String CommandLine {get;}
CurrentDirectory           Property   static System.String CurrentDirectory ...
ExitCode                   Property   static System.Int32 ExitCode {get;set;}
HasShutdownStarted         Property   static System.Boolean HasShutdownStart...
MachineName                Property   static System.String MachineName {get;}
NewLine                    Property   static System.String NewLine {get;}
OSVersion                  Property   static System.OperatingSystem OSVersio...
ProcessorCount             Property   static System.Int32 ProcessorCount {get;}
StackTrace                 Property   static System.String StackTrace {get;}
SystemDirectory            Property   static System.String SystemDirectory {...
TickCount                  Property   static System.Int32 TickCount {get;}
UserDomainName             Property   static System.String UserDomainName {g...
UserInteractive            Property   static System.Boolean UserInteractive ...
UserName                   Property   static System.String UserName {get;}
Version                    Property   static System.Version Version {get;}
WorkingSet                 Property   static System.Int64 WorkingSet {get;}
TickCount                               ExitCode

We can now select properties to view from System.Environment.

Displaying static properties of System.Environment

The properties of System.Environment are also static, and must be specified in a different way than normal properties. We use :: to indicate to Windows PowerShell that we want to work with a static method or property. To see the command that was used to launch Windows PowerShell, we check the CommandLine property by typing:

"C:\Program Files\Windows PowerShell\v1.0\powershell.exe"

To check the operating system version, display the OSVersion property by typing:

           Platform ServicePack         Version             VersionString
           -------- -----------         -------             -------------
            Win32NT Service Pack 2      5.1.2600.131072     Microsoft Windows...

We can check whether the computer is in the process of shutting down by displaying the HasShutdownStarted property:


Doing math with System.Math

The System.Math static class is useful for performing some mathematical operations. The class includes several useful methods, which we can display using Get-Member.


System.Math has several methods with the same name, but they're distinguished by the type of their parameters.

Type the following command to list the methods of the System.Math class.

[System.Math] | Get-Member -Static -MemberType Methods
   TypeName: System.Math

Name            MemberType Definition
----            ---------- ----------
Abs             Method     static System.Single Abs(Single value), static Sy...
Acos            Method     static System.Double Acos(Double d)
Asin            Method     static System.Double Asin(Double d)
Atan            Method     static System.Double Atan(Double d)
Atan2           Method     static System.Double Atan2(Double y, Double x)
BigMul          Method     static System.Int64 BigMul(Int32 a, Int32 b)
Ceiling         Method     static System.Double Ceiling(Double a), static Sy...
Cos             Method     static System.Double Cos(Double d)
Cosh            Method     static System.Double Cosh(Double value)
DivRem          Method     static System.Int32 DivRem(Int32 a, Int32 b, Int3...
Equals          Method     static System.Boolean Equals(Object objA, Object ...
Exp             Method     static System.Double Exp(Double d)
Floor           Method     static System.Double Floor(Double d), static Syst...
IEEERemainder   Method     static System.Double IEEERemainder(Double x, Doub...
Log             Method     static System.Double Log(Double d), static System...
Log10           Method     static System.Double Log10(Double d)
Max             Method     static System.SByte Max(SByte val1, SByte val2), ...
Min             Method     static System.SByte Min(SByte val1, SByte val2), ...
Pow             Method     static System.Double Pow(Double x, Double y)
ReferenceEquals Method     static System.Boolean ReferenceEquals(Object objA...
Round           Method     static System.Double Round(Double a), static Syst...
Sign            Method     static System.Int32 Sign(SByte value), static Sys...
Sin             Method     static System.Double Sin(Double a)
Sinh            Method     static System.Double Sinh(Double value)
Sqrt            Method     static System.Double Sqrt(Double d)
Tan             Method     static System.Double Tan(Double a)
Tanh            Method     static System.Double Tanh(Double value)
Truncate        Method     static System.Decimal Truncate(Decimal d), static...

This displays several mathematical methods. Here is a list of commands that demonstrate how some of the common methods work: