Not my type

In programming languages variables can be of a specific data type, such as integers or strings of characters.  If a language requires variable to be defined as containing only a specific class of data it is called strongly typed.  If the variables can contain any kind of data the language is weakly typed.  If the language is experimental it is prototyped. If it requires punch cards it is teletyped

http://www.staff.ncl.ac.uk/roger.broughton/museum/iomedia/images/pc6.jpg

As mentioned previously, everything in PowerShell is an object.  But simple scalar variables still have a data type.  PowerShell makes a best guess at what the type should be and does conversions on the fly so you usually don't have to worry about the data type of a variable or performing explicit conversions.

Here PowerShell converts the string to an integer, multiplies it with the floating point number, then adds the hexadecimal number.  When I give the answer it converts the integer to a string so it can be concatenated with the rest of the text.

Most of the time PowerShell correctly determines the data type and formats the output accordingly.  But what if you need to force a variable to be a specific type?  Precede either the variable or expression with the .NET value type enclosed in square brackets.  In this example we divide two numbers and cast the result as an integer and string respectively.

But that looks like it involves a bunch of typing.  Wouldn't it be nice if there was a shortcut to access those system types?  Yes it would be nice so that's why the nice people who made PowerShell included some type accelerators.  Instead of using [System.Int32] I can use [int] and instead of [System.String] I can use [string]

Are there many of these type accelerators available?  Yes there are. Oisen Grehan 's blog post not only shows all of the accelerators available but a handy way to list them all.  One that does not show up in the list is the [DateTime] accelerator for [System.DateTime].  Notice how flexible this value type is.

Now go back and check Oisen Grehan's blog post again.  There's all kinds of useful stuff that is just as flexible as the [DateTime] accelerator.  For example, there is the [ipaddress] data type that accepts a string and converts it to an IP address.

This is pretty sweet.  Notice that the type accelerator processes both IPv4 and IPv6 addresses.  If I need to prompt my user for an IP address I don't need to parse and validate it.  I can just assign it to a variable that has the [ipaddress] type and wrap it with some error handling then let .Net and PowerShell do the heavy lifting.

One other handy accelerator is the array type.  Why is it handy?  Because it gives us access to all of the methods for the .Net array class.  To access any of the .Net class methods specify the class in square brackets followed by two colons and then the method.

Note that that when calling these methods they only operate on the variable you pass.  If you need to keep the array in its original state you need to copy it first and then call the method on the copy.

Type accelerators are one of PowerShell's many useful and time saving capabilities.  If you never introduce yourself you might not know that PowerShell is just your type.