Remove leading zeros in powershell

Question

I have several strings and try to remove the leading zeros for them. I know I can use TrimStart() but it's wrong if all numbers are zero.

$Test = "00000.22"
$Test = $Test.trimstart('0')

The result is .22 and what I expect is 0.22. How can I achieve it? Thank you.

Answer 1

A purely textual solution is to use the -replace operator with a regular expression:

PS> '00000.22' -replace '^0+', '0' 
0.22

^0+ matches one or more (+) zeros at the start (^) of the string and replaces them with a single zero.

If you also want to make sure that numbers with an integral part that isn't 0 and/or without a fractional part are properly handled, use -replace '^0+(?=[^.])' (note the absence of a substitution operand, which effectively removes what gets matched):

PS> ('00000.22', '0000', '00001.22').ForEach({ $_ -replace '^0+(?=[^.])' })
0.22
0
1.22

Positive look-ahead assertion (?=[^.]) effectively removes all leading zeros (^0+) as long as such a zero isn't followed by a literal . ([^.]).

^{If you do want something like '00000.22' to become just '.22', i.e. if you want to drop the integral part if it happens to be 0, the regex becomes simpler: '^0+(?=.)'}

---

gms0ulman's answer is convenient and probably works fine in most cases, but there are pitfalls:

• You're changing the data type to [decimal], and converting that back to a string can result in a culture-specific representation where . is converted to , (that said, PowerShell itself often applies the invariant culture, which always uses .); e.g.:

    # Cast to [decimal] using the German culture ('de')
    PS> [System.Threading.Thread]::CurrentThread.CurrentCulture = 'de'; [decimal] '0000.22'
    0,22  # !! Note the "," instead of "."
  

• Even though unlikely with a high-precision data type such as [decimal], rounding errors are possible:

    PS> [decimal] '00.99999999999999999999999999999'
    1.0000000000000000000000000000 # !! rounding occurred