Removing variables

To remove variable, use command Remove-Variable with the name of the variable (without the $)

PS C:\> $years
Name                           Value
----                           -----
Marek                          41
Andrzej                        20
Kamil                          32
Bartosz                        39

PS C:\> Remove-Variable years
PS C:\> $years
PS C:\>

Converting Variables

To change the type of the variable, we need to convert it.

The simplest way is by declaring the new type of the variable

PS H:\> $a="3"
PS H:\> $a.gettype()

IsPublic IsSerial Name                                     BaseType                                         
-------- -------- ----                                     --------                                         
True     True     String                                   System.Object                                    

PS H:\> $a=[int] $a
PS H:\> $a
3

PS H:\> $a.gettype()

IsPublic IsSerial Name                                     BaseType                                         
-------- -------- ----                                     --------                                         
True     True     Int32                                    System.ValueType           
PS H:\> $b="HELLO"

PS H:\> $b
HELLO

PS H:\> $b.GetType()
IsPublic IsSerial Name                                     BaseType                                         
-------- -------- ----                                     --------                                         
True     True     String                                   System.Object                                    

PS H:\> $b=[int] $b
Cannot convert value "HELLO" to type "System.Int32". Error: "Input string was not in a correct format."
At line:1 char:1
+ $b=[int] $b
+ ~~~~~~~~~~~
    + CategoryInfo          : InvalidArgument: (:) [], RuntimeException
    + FullyQualifiedErrorId : InvalidCastFromStringToInteger 

As You can see, we cannot convert word Hello to the Integer 😉

TIP

If you want to create a variable with the defined type and not let it create automatically, you can do it like that:

PS H:\> [array]$a="test"
PS H:\> $a.gettype()
IsPublic IsSerial Name                                     BaseType                                         
-------- -------- ----                                     --------                                         
True     True     Object[]                                 System.Array         

Methods of the variable

To find out, what kind of methods are available to the variable we need to use get-member (alias gm)

PS H:\> $a="234"
PS H:\> $a|gm

   TypeName: System.String

Name             MemberType            Definition                                                           
----             ----------            ----------                                                           
Clone            Method                System.Object Clone(), System.Object ICloneable.Clone()              
CompareTo        Method                int CompareTo(System.Object value), int CompareTo(string strB), in...
Contains         Method                bool Contains(string value)                                          
………………

We can also convert this string to the another format using proper method

PS H:\> $b=$a.ToDouble($null)
PS H:\> $b.gettype()
IsPublic IsSerial Name                                     BaseType                                         
-------- -------- ----                                     --------                                         
True     True     Double                                   System.ValueType           

Exercise

1. Create a variable $a and assign it a value of 3 then use the write-host command to display the value.
2. Type $a.GetType() to find the type of variable $a
3. Create a variable $b and assign it a value of 3.3 then use the write-host command to display the value.
4. Type $b.GetType() to find the type of variable $b
5. Create a variable $c and assign it a value of “3.3” (include those quotes) then use the write-host command to display the value.
6. Type $c.GetType() to find the type of variable $c
7. Assign to a variable $d the sum of the first two variables by typing $d=$a + $b
8. What value is returned when you convert to integer the values 3.4 and 3.6?

Check last page for the result.