CODEWITHSUNDEEP
arrayspowershell
BEEBUG
BEEBUG

Reputation: 35

Building a sequential string into an array (quickly)

I've written the following code to build an array with sequential strings. It works like I expect, but I wish it ran quicker. Is there a more efficient way to produce my desired results in PowerShell?

I'm very new to PowerShell and appreciate your coaching.

$MIN = 1
$MAX = 20000
$ARRAY = @()
$PREFIX = "AA"

$startDTM = (Get-Date) # Start time
FOR ($i=$MIN; $i -le $MAX; $i++)
{
   If ($i -gt 0 -and $i -lt 10) {
     $ARRAY = $ARRAY + ($PREFIX+"00000"+$i)
   }
   If ($i -gt 9 -and $i -lt 100) {
     $ARRAY = $ARRAY + ($PREFIX+"0000"+$i)
   }
   If ($i -gt 99 -and $i -lt 1000) {
     $ARRAY = $ARRAY + ($PREFIX+"000"+$i)
   }
   If ($i -gt 999 -and $i -lt 10000) {
     $ARRAY = $ARRAY + ($PREFIX+"00"+$i)
   }
   If ($i -gt 9999 -and $i -lt 100000) {
     $ARRAY = $ARRAY + ($PREFIX+"0"+$i)
   }
   If ($i -gt 99999 -and $i -lt 1000000) {
     $ARRAY = $ARRAY + ($PREFIX+$i)
   }
}
$endDTM = (Get-Date) #End Time
"Elapsed Time: $(($endDTM-$startDTM).totalseconds) seconds"
$ARRAY.count  #How many loaded.

Example of $ARRAY:

AA000001
AA000002
...
AA019999
AA020000

Upvotes: 2

Views: 147

Answers (1)

Martin Brandl
Martin Brandl

Reputation: 58931

The following one-liner tooked 0.4911672 seconds (your example 12.9638944 seonds). Results are the same. It uses the format string with decimal specifier to ensure there are 6 digits and just store the result in the array:

$MIN = 1
$MAX = 20000
$PREFIX = "AA"

$ARRAY = $MIN .. $MAX | % { "$PREFIX{0:D6}" -f $_ }

You can further improove the performance by using a while loop (thanks 4c74356b41 for mentioning that):

# ....
$array = while ($MIN -le $MAX) 
{
   "$PREFIX{0:D6}" -f $MIN++
}

This tooked 0.0970327 seconds on my computer.

Upvotes: 2

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