There are many different ways to add leading zeros to a number in PowerShell. In practice, numbers (object type: [int]) cannot have leading zeros, so we are really creating a text value (object type: [string]) that contains the number.

In the examples below, I pad the number 42 to four digits (0042). Of course, you can adjust the length of the padding as needed :)

I also demonstrate the following options (and a few more) in this video on YouTube.

With the format operator

My personal favorite is the format operator -f:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13

$Number = 42

# Specify 4 digits as a number:
"{0:d4}" -f $Number

# Alternatively: enter the desired number of zeros directly:
"{0:0000}" -f $Number

# Alternatively: control the number with a variable
$Digits = 4 # for 4 digits
"{0:d$Digits}" -f $Number

# Each returns: 0042

If you want to generate a computer name with a fixed length, for example, you could do something like this:

1
2
3
4

$Number = 42

"PC{0:d4}" -f $Number
# Returns: PC0042

The format operator can do more. For a first overview, I recommend this page on SS64.com.

[int].ToString() method

Another option is to use the .ToString() method of an [int] object:

1
2
3
4
5
6
7

$Number = 42

$Number.ToString("d4")

$Number.ToString("0000")

# Each returns: 0042

[String].PadLeft() method

This might also be useful in some scenarios: the .PadLeft() method of a [String] object. Since we start here with a number [int], we first convert it to a string using ToString(). It would also be possible to add the zeros during the string conversion itself (see section [int].ToString() method), but I still find it interesting to mention .PadLeft(). Perhaps you can use it for something else.

1
2
3
4
5
6

$Number = 42

# The quotes around the "0" are important!
$Number.ToString().PadLeft(4, "0")

# Returns: 0042

If you ever want to pad with characters on the right, there is also .PadRight():

1
2
3
4
5
6

$Number = 42

# The quotes around the "0" are important!
$Number.ToString().PadRight(4, "0")

# Returns: 4200