Review of PowerShell Maths

Windows PowerShell Maths

PowerShell is very good at understand whether a command in your script should be handled as text or as a number.  Incidentally, the more you study PowerShell’s different math techniques, the more reasons you will find to turn to PowerShell rather than VBScript or Excel.

Topics for PowerShell Maths

For once, I favour the English word maths (plural) because we are dealing with numerous aspects of math calculation.

1. Simple Arithmetic Operations in PowerShell
2. PowerShell [Math]::Static Methods
3. Measure-Object Cmdlet
4. Get-Date Cmdlet
5. PowerShell’s Concatenator (+)
6. PowerShell ‘=’ Sign and -eq Operator
7. Counters for Loops $i++

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Review of Basic PowerShell Mathematics

Get started by simply typing numbers at the PowerShell command line.  You can use the 4 well-known operators + – * (asterisk) and / (forward slash), try these calculations:

Simple Arithmetic Operations in PowerShell

PowerShell handles basic maths calculations, such as add and multiply with deceptive ease. Try these simple arithmetic computations:

Putting PowerShell Maths to Work

Suppose you want to test a router connection.  We could use ping, but I have chosen Win32_PingStatus.  The point is that Microsoft has designed PowerShell so that it can deal with adding 1 to 192.168.1.1.

Note 1: A StatusCode of 0 means a successful ping; 11003 is the equivalent of 'Destination host unreachable'.

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Review of PowerShell [Math]::Static Methods

Thanks to PowerShell accessing .Net Framework, we can perform trickier math operations; observe the static syntax, [Math]::function().  The key point here is we are asking PowerShell to employ functions such as you would use in Excel.

Note 2: Strictly speaking we should use [System.Math], however, the shorter [Math] works just fine.  See more on PowerShell’s static math functions.

Putting PowerShell Maths to Work

In this scenario we are investigating why a disk labelled 1 terabyte was actually only 931 gigabytes.

Result: 1000202273280 (Bytes)

Let us employ PowerShell’s [Math]::Round static method to crack the problem.  Also observe where we divide by GB (gigabyte)

Result: 931.51 GB (GigaBytes)

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PowerShell’s Concatenator (+)

Joining text strings in PowerShell is very easy, just call for the plus sign; you can even combine text strings with numbers.  Observe how seamlessly the simple plus (+) sign joins text, numbers and the result of calculations.

The only danger is overthink, looking for extra syntax when all you need is (+)

A more likely scenario would be combining fields, for example concatenating values stored in variables.

My next example is more interesting because it uses [System.Datetime] and also the static function [Math]::Truncate.

Note 3: Trace the $Age variable; once again you can append a number to a text string.

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PowerShell -eq and ‘=’ Sign

For a purely mathematical calculation PowerShell uses the -eq conditional operator. The only place beginners see the equals sign in PowerShell is when assigning variables.

The -eq operator has a whole family of relatives, such as -ne (not equal), and then also the branch of the family containing greater than and less than, (-gt and -lt).

Mission: To Find Zero Length Files
Key command: Where-Object {$_.length -eq 0}

Note 4: Observe the use of ‘=’ to declare variables; but -eq for the actual comparison operator.

See much more on PowerShell’s comparison operators »

Summary:  Review of Windows PowerShell Maths

PowerShell always makes an effort to understand whether your code is text or a number.  The secret of handling more complex maths functions is to understand [System.Math]:: static functions.

See more PowerShell examples of math operations

• PowerShell Maths Index   • Windows PowerShell   • PowerShell Splatting

• PowerShell Math  • Comparison Operators   • PowerShell Measure Object   • Measure Command

• PowerShell Tutorials  • Syntax  • Pipeline  • PowrShell Quotes  • Free WMI Monitor

Please email me if you have a better example script. Also please report any factual mistakes, grammatical errors or broken links, I will be happy to correct the fault.