Split a string with powershell to get the first and last element

问题

If you do: git describe --long

you get: 0.3.1-15-g3b885c5

Thats the meaning of the above string:

Tag-CommitDistance-CommitId (http://git-scm.com/docs/git-describe)

How would you split the string to get the first (Tag) and last (CommitId) element?

回答1:

By using String.split() with the count parameter to manage dashes in the commitid:

$x = "0.3.1-15-g3b885c5"
$tag = $x.split("-",3)[0]
$commitid = $x.split("-",3)[-1]

回答2:

Note: This answer focuses on improving on the split-into-tokens-by-- approach from Ocaso Protal's helpful answer.
However, that approach isn't fully robust, because git tag names may themselves contain - characters, so you cannot blindly assume that the first - instance ends the full tag name.
To account for that, use Richard's robust solution instead.

---

Just to offer a more PowerShell-idiomatic variant:

$tag, $commitId = ('0.3.1-15-g3b885c5' -split '-')[0, -1]

• PowerShell's -split operator is used to split the input string into an array of tokens by separator -
  While the [string] type's .Split() method would be sufficient here, -split offers many advantages in general.

• [0, -1] extracts the first (0) and last (-1) element from the array returned by -split and returns them as a 2-element array.

• $tag, $commitId = is a destructuring assignment that assigns the elements of the resulting 2-element array to a variable each.

回答3:

I can't recall if dashes are allowed in tags, so I'll assume they are, but will not appear in the last two fields.

Thus:

if ("0.3.1-15-g3b885c5" -match '(.*)-\d+-([^-]+)') {
  $tag = $Matches[1];
  $commitId = $Matches[2]
}

来源：https://stackoverflow.com/questions/32095674/split-a-string-with-powershell-to-get-the-first-and-last-element