In December of 2014, I decided that my life in 2015 was in need of some push-ups. Instead of just starting with 10 a day, or some other arbitrary number, I thought I would do as many push-ups a day as it was the day in the year. This meant that on day one (January 1, 2015), I would do one push-up and on day two, I would do two push-ups, and so on. Today is the 20th day of the new year, and so I’ll have to do 20 tonight. I wanted to know how many push-ups I will have done by January 31st. Being the Windows PowerShell hobbyist that I am, I enlisted PowerShell to do my calculations for me.

I started with a variable, $EndDay, and the range operator (..). The combination of the two provides me an integer array of the days in January, such as 1..$EndDay (or, 1..31). Using this, I can calculate how many total push-ups I will have done by the end of the day on January 31st. The example below sets up the integer array, as well as the ForEach-Object loop where we’ll do our calculations. Note: I’m using the ForEach-Object alias, foreach.

$EndDay = 31
1..$EndDay | foreach {

}

The first thing we do, below, is include a second variable, $PushUps, that will collect the total number of push-ups for the month. We’ll use the += assignment operator. This operator takes whatever is already in $PushUps, and adds to it. If the current value stored in $PushUps was 1, and we used the += assignment operator like so, $PushUps += 2, then the value in $PushUps would be 3 (1 + 2 is equal to 3). If we used the standard assignment operator (=), then $PushUps would be 2, as 1 would be overwritten.

On the next line, below, we write some information on the screen. We write the current day: that’s the current number from the integer array represented by $_ (as of PowerShell 3.0, $_ can be represented as $PSItem). Then we write out the total number of push-ups completed by that day: $PushUps.

$EndDay = 31
1..$EndDay | foreach {
    $PushUps += $_
    Write-Output -Verbose "Day: $_ / PushUp Total: $PushUps"
}

I noticed that when I reran the code in the ISE, that the value of $PushUps was incorrect on the second run. This is because the variable already exists, and by the end of the first run already contains 496—the number of push-ups I’ll have done by the end of January! Therefore, I added an If statement that removed the $PushUps variable when $_ was equal to $EndDay. This happens on the final run through the foreach.

$EndDay = 31
1..$EndDay| foreach {
    $PushUps += $_
    Write-Output -Verbose "Day: $_ / PushUp Total: $PushUps"
    If ($_ -eq $EndDay) {
        Remove-Variable PushUps
    }
}

If you change the value for $EndDay to 365, you’ll be able to determine that after December 31st (if I can somehow keep this up) I will have done 66,299 total push-ups for the year. It’s hard to imagine that I could do 365 push-ups at once, but then again, it’s hard to imagine I’ll get though the rest of the month. Here’s an image that shows the the full results when we run the function above.

Thanks for reading, and wish me good luck—I’m going to need it.