Extract file extension: Difference between revisions

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If your programming language (or standard library) has built-in functionality for extracting a filename extension, show how it would be used, and ~~clearly~~ ~~state how~~ its behavior differs from this specification.

If your programming language (or standard library) has built-in functionality for extracting a filename extension, show how it would be used and how exactly its behavior differs from this specification.

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|

|-

| <code>~~characterModel~~.3D</code>

| <code>CharacterModel.3DS</code>

| <code>.3D</code>

| <code>.3DS</code>

|

|-

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=={{header|Perl 6}}==

The built-in <code>.IO~~.extension~~</code> ~~method~~ ~~can~~ be ~~used, but it..~~.

The built-in <code>IO::Path</code> class has an <code>.extension</code> method:

<lang perl6>say $path.IO.extension;</lang>

Contrary to this task's specification, it

* doesn't include the dot in the output

* doesn't restrict ~~extensions~~ to letters and numbers.

* doesn't restrict the extension to letters and numbers.

⚫

Here's a custom implementation which does satisfy ~~those~~ requirements:

⚫

Here's a custom implementation which does satisfy the task requirements:

⚫

<lang perl6>sub extension (Str $~~filename~~ --> Str) {

⚫

$~~filename~~.match(/:i ['.' <+alpha-[_]>+]? $ /).Str

⚫

<lang perl6>sub extension (Str $path --> Str) {

⚫

$path.match(/:i ['.' <+alpha-[_]>+]? $ /).Str

}</lang>

Testing:

<lang perl6>~~say~~ "$_ -> ~~{(extension~~ $_).perl}" ~~for~~

<lang perl6>printf "%-35s %-11s %-12s\n", $_, extension($_).perl, $_.IO.extension.perl

for <

'mywebsite.com/picture/image.png',

'http://~~mywebsite~~.com/~~picture/image~~.~~png',~~

http://example.com/download.tar.gz

CharacterModel.3DS

'myuniquefile.longextension',

.desktop

'IAmAFileWithoutExtension',

document

'/path/to.my/file',

~~'file~~.~~odd_one',~~

document.txt_backup

/etc/pam.d/login

;</lang>

>;</lang>

<pre>

http://example.com/download.tar.gz ".gz" "gz"

mywebsite.com/picture/image.png -> ".png"

CharacterModel.3DS ".3DS" "3DS"

http://mywebsite.com/picture/image.png -> ".png"

.desktop ".desktop" "desktop"

myuniquefile.longextension -> ".longextension"

document "" ""

IAmAFileWithoutExtension -> ""

document.txt_backup "" "txt_backup"

/path/to.my/file -> ""

/etc/pam.d/login "" ""

file.odd_one -> ""

</pre>