How to easier manipulate timespan in powershell - shell

Question

I am doing an assignment for Powershell and one of the functions is to say when the last boot was. I am printing date and 'time since', date works fine but I think there is too much code for displaying the 'time since'. I want the first value to not be zero. Like this:
1 Hour, 0 Minutes, 34 Seconds
and not like this:
0 Days, 1 Hours, 0 Minutes, 34 Seconds
$bootDate = (Get-CimInstance Win32_OperatingSystem).LastBootUpTime
$bootTime = $(Get-Date).Subtract($bootDate)
# Think there is an easier way, but couldn't find any :/
$time = ""
if($bootTime.Days -ne 0) {
$time = "$($bootTime.Days) Days, $($bootTime.Hours) Hours, $($bootTime.Minutes) Minutes, "
} elseif($bootTime.Hours -ne 0){
$time = "$($bootTime.Hours) Hours, $($bootTime.Minutes) Minutes, "
} elseif($bootTime.Minutes -ne 0){
$time = "$($bootTime.Minutes) Minutes, "
}
echo "Time since last boot: $time$($bootTime.Seconds) Seconds"
echo "Date and time: $($bootDate.DateTime)"
This code prints it as I want it to be, but is just seems like too much code for something so little. Is there an easier way?

Answer 1

Make sure you inspect to TotalDays rather than Days. Additionally, I would split the code into a separate function:
function Get-TruncatedTimeSpan {
param([timespan]$TimeSpan)
$time = ""
if($TimeSpan.TotalDays -ge 1) {
$time += "$($TimeSpan.Days) Days, "
}
if($TimeSpan.TotalHours -ge 1){
$time += "$($TimeSpan.Hours) Hours, "
}
if($TimeSpan.TotalMinutes -ge 1){
$time += "$($TimeSpan.Minutes) Minutes, "
}
return "$time$($TimeSpan.Seconds) Seconds"
}
$bootDate = (Get-CimInstance Win32_OperatingSystem).LastBootUpTime
$bootTime = $(Get-Date).Subtract($bootDate)
echo "Time since last boot: $(Get-TruncatedTimeSpan $bootTime)"
echo "Date and time: $($bootDate.DateTime)"

Answer 2

A concise solution based on removing the longest run of 0-valued components from the start, using the -replace operator, which uses a regular expression for matching (and by not specifying a replacement string effectively removes the match):
function get-FriendlyTimespan {
param([timespan] $TimeSpan)
"{0} Days, {1} Hours, {2} Minutes, {3} Seconds" -f
$TimeSpan.Days, $TimeSpan.Hours, $TimeSpan.Minutes, $TimeSpan.Seconds -replace
'^0 Days, (0 Hours, (0 Minutes, )?)?'
}
# Invoke with sample values (using string-based initialization shortcuts):
"0:0:1", "0:1:0", "1:0:0", "1", "0:2:33" | % { get-FriendlyTimespan $_ }
The above yields:
1 Seconds
1 Minutes, 0 Seconds
1 Hours, 0 Minutes, 0 Seconds
1 Days, 0 Hours, 0 Minutes, 0 Seconds
2 Minutes, 33 Seconds