Checks and fixups
=================

The quality checks help catch common translator errors, ensuring the
translation is in good shape. The checks can be ignored in case of false positives.

Once submitting a translation with a failing check, this is immediately shown to
the user:

.. image:: /images/checks.png


.. _autofix:

Automatic fixups
----------------

In addition to :ref:`checks`, Weblate can also fix some common
errors in translated strings automatically. Use it with caution to not have
it add errors.

.. seealso::

   :setting:`AUTOFIX_LIST`

.. _checks:

Quality checks
--------------

Weblate employs a wide range of quality checks on strings. The following section
describes them all in further detail. There are also language specific checks.
Please file a bug if anything is reported in error.

.. seealso::

   :setting:`CHECK_LIST`, :ref:`custom-checks`

Translation checks
------------------

Executed upon every translation change, helping translators maintain
good quality translations.

.. _check-bbcode:

BBcode markup
~~~~~~~~~~~~~

*BBcode in translation does not match source*

BBCode represents simple markup, like for example highlighting important parts of a
message in bold font, or italics.

This check ensures they are also found in translation.

.. note::

    The method for detecting BBcode is currently quite simple so this check
    might produce false positives.

.. _check-duplicate:

Consecutive duplicated words
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

*Text contains the same word twice in a row:*

.. versionadded:: 4.1

Checks that no consecutive duplicate words occur in a translation. This usually
indicates a mistake in the translation.

.. hint::

   This check includes language specific rules to avoid false positives. In
   case it triggers falsely in your case, let us know. See :ref:`report-issue`.


.. _check-double-space:

Double space
~~~~~~~~~~~~

*Translation contains double space*

Checks that double space is present in translation to avoid false positives on other space-related checks.

Check is false when double space is found in source meaning double space is intentional.


.. _check-angularjs-format:
.. _check-c-format:
.. _check-c-sharp-format:
.. _check-es-format:
.. _check-i18next-interpolation:
.. _check-java-format:
.. _check-java-messageformat:
.. _check-javascript-format:
.. _check-percent-placeholders:
.. _check-perl-format:
.. _check-php-format:
.. _check-python-brace-format:
.. _check-python-format:
.. _check-qt-format:
.. _check-qt-plural-format:
.. _check-ruby-format:

Formatted strings
~~~~~~~~~~~~~~~~~

Checks that formatting in strings are replicated between both source and translation.
Omitting format strings in translation usually causes severe problems, so the formatting in strings
should usually match the source.

Weblate supports checking format strings in several languages. The check is not
enabled automatically, only if a string is flagged appropriately (e.g.
`c-format` for C format). Gettext adds this automatically, but you will
probably have to add it manually for other file formats or if your PO files are
not generated by :program:`xgettext`.

This can be done per unit (see :ref:`additional`) or in :ref:`component`.
Having it defined per component is simpler, but can lead to false positives in
case the string is not interpreted as a formatting string, but format string syntax
happens to be used.

.. hint::

   In case specific format check is not available in Weblate, you can use
   generic :ref:`check-placeholders`.

Besides checking, this will also highlight the formatting strings to easily
insert them into translated strings:

.. image:: /images/format-highlight.png

AngularJS interpolation string
******************************

*AngularJS interpolation strings do not match source*

+----------------------+------------------------------------------------------------+
| Named format string  | ``Your balance is {{amount}} {{ currency }}``              |
+----------------------+------------------------------------------------------------+
| Flag to enable       | `angularjs-format`                                         |
+----------------------+------------------------------------------------------------+

.. seealso::

    `AngularJS: API: $interpolate <https://docs.angularjs.org/api/ng/service/$interpolate>`_

C format
********

*C format string does not match source*

+------------------------+------------------------------------------------------------+
| Simple format string   | ``There are %d apples``                                    |
+------------------------+------------------------------------------------------------+
| Position format string | ``Your balance is %1$d %2$s``                              |
+------------------------+------------------------------------------------------------+
| Flag to enable         | `c-format`                                                 |
+------------------------+------------------------------------------------------------+

.. seealso::

    `C format strings <https://www.gnu.org/software/gettext/manual/html_node/c_002dformat.html>`_,
    `C printf format <https://en.wikipedia.org/wiki/Printf_format_string>`_

C# format
*********

*C# format string does not match source*

+------------------------+------------------------------------------------------------+
| Position format string | ``There are {0} apples``                                   |
+------------------------+------------------------------------------------------------+
| Flag to enable         | `c-sharp-format`                                           |
+------------------------+------------------------------------------------------------+

.. seealso::

    `C# String Format <https://docs.microsoft.com/en-us/dotnet/api/system.string.format?view=netframework-4.7.2>`_

ECMAScript template literals
****************************

*ECMAScript template literals do not match source*

+------------------------+------------------------------------------------------------+
| Interpolation          | ``There are ${number} apples``                             |
+------------------------+------------------------------------------------------------+
| Flag to enable         | `es-format`                                                |
+------------------------+------------------------------------------------------------+

.. seealso::

    `Template literals <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals>`_

i18next interpolation
*********************

*The i18next interpolation does not match source*

.. versionadded:: 4.0

+------------------------+------------------------------------------------------------+
| Interpolation          | ``There are {{number}} apples``                            |
+------------------------+------------------------------------------------------------+
| Nesting                | ``There are $t(number) apples``                            |
+------------------------+------------------------------------------------------------+
| Flag to enable         | `i18next-interpolation`                                    |
+------------------------+------------------------------------------------------------+

.. seealso::

    `i18next interpolation <https://www.i18next.com/translation-function/interpolation>`_


Java format
***********

*Java format string does not match source*

+------------------------+------------------------------------------------------------+
| Simple format string   | ``There are %d apples``                                    |
+------------------------+------------------------------------------------------------+
| Position format string | ``Your balance is %1$d %2$s``                              |
+------------------------+------------------------------------------------------------+
| Flag to enable         | `java-format`                                              |
+------------------------+------------------------------------------------------------+

.. seealso::

    `Java Format Strings <https://docs.oracle.com/javase/7/docs/api/java/util/Formatter.html>`_


Java MessageFormat
******************

*Java MessageFormat string does not match source*

+------------------------+------------------------------------------------------------+
| Position format string | ``There are {0} apples``                                   |
+------------------------+------------------------------------------------------------+
| Flag to enable         | `java-messageformat` enables the check unconditionally     |
+------------------------+------------------------------------------------------------+
|                        | `auto-java-messageformat` enables check only if there is a |
|                        | format string in the source                                |
+------------------------+------------------------------------------------------------+

.. seealso::

   `Java MessageFormat <https://docs.oracle.com/javase/7/docs/api/java/text/MessageFormat.html>`_

JavaScript format
*****************

*JavaScript format string does not match source*

+------------------------+------------------------------------------------------------+
| Simple format string   | ``There are %d apples``                                    |
+------------------------+------------------------------------------------------------+
| Flag to enable         | `javascript-format`                                        |
+------------------------+------------------------------------------------------------+

.. seealso::

    `JavaScript formatting strings <https://www.gnu.org/software/gettext/manual/html_node/javascript_002dformat.html>`_

Percent placeholders
********************

*The percent placeholders do not match source*

.. versionadded:: 4.0

+------------------------+------------------------------------------------------------+
| Simple format string   | ``There are %number% apples``                              |
+------------------------+------------------------------------------------------------+
| Flag to enable         | `percent-placeholders`                                     |
+------------------------+------------------------------------------------------------+


Perl format
***********

*Perl format string does not match source*

+------------------------+------------------------------------------------------------+
| Simple format string   | ``There are %d apples``                                    |
+------------------------+------------------------------------------------------------+
| Position format string | ``Your balance is %1$d %2$s``                              |
+------------------------+------------------------------------------------------------+
| Flag to enable         | `perl-format`                                              |
+------------------------+------------------------------------------------------------+

.. seealso::

    `Perl sprintf <https://perldoc.perl.org/functions/sprintf.html>`_,
    `Perl Format Strings <https://www.gnu.org/software/gettext/manual/html_node/perl_002dformat.html>`_

PHP format
**********

*PHP format string does not match source*

+------------------------+------------------------------------------------------------+
| Simple format string   | ``There are %d apples``                                    |
+------------------------+------------------------------------------------------------+
| Position format string | ``Your balance is %1$d %2$s``                              |
+------------------------+------------------------------------------------------------+
| Flag to enable         | `php-format`                                               |
+------------------------+------------------------------------------------------------+

.. seealso::

    `PHP sprintf documentation <https://www.php.net/manual/en/function.sprintf.php>`_,
    `PHP Format Strings <https://www.gnu.org/software/gettext/manual/html_node/php_002dformat.html>`_


Python brace format
*******************

*Python brace format string does not match source*

+----------------------+------------------------------------------------------------+
| Simple format string | ``There are {} apples``                                    |
+----------------------+------------------------------------------------------------+
| Named format string  | ``Your balance is {amount} {currency}``                    |
+----------------------+------------------------------------------------------------+
| Flag to enable       | `python-brace-format`                                      |
+----------------------+------------------------------------------------------------+

.. seealso::

    :ref:`Python brace format <python:formatstrings>`,
    `Python Format Strings <https://www.gnu.org/software/gettext/manual/html_node/python_002dformat.html>`_

Python format
*************

*Python format string does not match source*

+----------------------+------------------------------------------------------------+
| Simple format string | ``There are %d apples``                                    |
+----------------------+------------------------------------------------------------+
| Named format string  | ``Your balance is %(amount) %(currency)``                  |
+----------------------+------------------------------------------------------------+
| Flag to enable       | `python-format`                                            |
+----------------------+------------------------------------------------------------+

.. seealso::

    :ref:`Python string formatting <python:old-string-formatting>`,
    `Python Format Strings <https://www.gnu.org/software/gettext/manual/html_node/python_002dformat.html>`_

Qt format
*********

*Qt format string does not match source*

+------------------------+------------------------------------------------------------+
| Position format string | ``There are %1 apples``                                    |
+------------------------+------------------------------------------------------------+
| Flag to enable         | `qt-format`                                                |
+------------------------+------------------------------------------------------------+

.. seealso::

    `Qt QString::arg() <https://doc.qt.io/qt-5/qstring.html#arg>`_

Qt plural format
****************

*Qt plural format string does not match source*

+------------------------+------------------------------------------------------------+
| Plural format string   | ``There are %Ln apple(s)``                                 |
+------------------------+------------------------------------------------------------+
| Flag to enable         | `qt-plural-format`                                         |
+------------------------+------------------------------------------------------------+

.. seealso::

    `Qt i18n guide <https://doc.qt.io/qt-5/i18n-source-translation.html#handling-plurals>`_

Ruby format
***********

*Ruby format string does not match source*

+------------------------+------------------------------------------------------------+
| Simple format string   | ``There are %d apples``                                    |
+------------------------+------------------------------------------------------------+
| Position format string | ``Your balance is %1$f %2$s``                              |
+------------------------+------------------------------------------------------------+
| Named format string    | ``Your balance is %+.2<amount>f %<currency>s``             |
+------------------------+------------------------------------------------------------+
| Named template string  | ``Your balance is %{amount} %{currency}``                  |
+------------------------+------------------------------------------------------------+
| Flag to enable         | `ruby-format`                                              |
+------------------------+------------------------------------------------------------+

.. seealso::

    `Ruby Kernel#sprintf <https://ruby-doc.org/core/Kernel.html#method-i-sprintf>`_

.. _check-translated:

Has been translated
~~~~~~~~~~~~~~~~~~~

*This string has been translated in the past*

Means a string has been translated already. This can happen when the
translations have been reverted in VCS or lost otherwise.

.. _check-inconsistent:

Inconsistent
~~~~~~~~~~~~

*This string has more than one translation in this project or is not translated
in some components.*

Weblate checks translations of the same string across all translation within a
project to help you keep consistent translations.

The check fails on differing translations of one string within a project. This
can also lead to inconsistencies in displayed checks. You can find other
translations of this string on the :guilabel:`Other occurrences` tab.

.. note::

   This check also fires in case the string is translated in one component and
   not in another. It can be used as a quick way to manually handle strings
   which are not translated in some components just by clicking on the
   :guilabel:`Use this translation` button displayed on each line in the
   :guilabel:`Other occurences` tab.

   You can use :ref:`addon-weblate.autotranslate.autotranslate` addon to
   automate translating of newly added strings which are already translated in
   another component.

.. seealso::

   :ref:`translation-consistency`


.. _check-kashida:

Kashida letter used
~~~~~~~~~~~~~~~~~~~

*The decorative kashida letters should not be used*

.. versionadded:: 3.5

The decorative Kashida letters should not be used in translation. These are
also known as Tatweel.

.. seealso::

   `Kashida on Wikipedia <https://en.wikipedia.org/wiki/Kashida>`_

.. _check-md-link:

Markdown links
~~~~~~~~~~~~~~

*Markdown links do not match source*

.. versionadded:: 3.5

Markdown links do not match source.

.. seealso::

   `Markdown links`_


.. _check-md-reflink:

Markdown references
~~~~~~~~~~~~~~~~~~~

*Markdown link references do not match source*

.. versionadded:: 3.5

Markdown link references do not match source.

.. seealso::

   `Markdown links`_

.. _check-md-syntax:

Markdown syntax
~~~~~~~~~~~~~~~

*Markdown syntax does not match source*

.. versionadded:: 3.5

Markdown syntax does not match source

.. seealso::

   `Markdown span elements`_

.. _Markdown links: https://daringfireball.net/projects/markdown/syntax#link
.. _Markdown span elements: https://daringfireball.net/projects/markdown/syntax#span

.. _check-max-length:

Maximum length of translation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

*Translation should not exceed given length*

Checks that translations are of acceptable length to fit available space.
This only checks for the length of translation characters.

Unlike the other checks, the flag should be set as a ``key:value`` pair like
``max-length:100``.

.. hint::

   This checks looks at number of chars, what might not be the best metric when
   using proportional fonts to render the text. The :ref:`check-max-size` check
   does check actual rendering of the text.

   The ``replacements:`` flag might be also useful to expand placeables before
   checking the string.

.. _check-max-size:

Maximum size of translation
~~~~~~~~~~~~~~~~~~~~~~~~~~~

*Translation rendered text should not exceed given size*

.. versionadded:: 3.7

Translation rendered text should not exceed given size. It renders the text
with line wrapping and checks if it fits into given boundaries.

This check needs one or two parameters - maximal width and maximal number of
lines. In case the number of lines is not provided, one line text is
considered.

You can also configure used font by ``font-*`` directives (see
:ref:`custom-checks`), for example following translation flags say that the
text rendered with ubuntu font size 22 should fit into two lines and 500
pixels:

.. code-block:: text

   max-size:500:2, font-family:ubuntu, font-size:22

.. hint::

   You might want to set ``font-*`` directives in :ref:`component` to have the same
   font configured for all strings within a component. You can override those
   values per string in case you need to customize it per string.

   The ``replacements:`` flag might be also useful to expand placeables before
   checking the string.

.. seealso::

   :ref:`fonts`, :ref:`custom-checks`, :ref:`check-max-length`

.. _check-escaped-newline:

Mismatched \n
~~~~~~~~~~~~~

*Number of \n in translation does not match source*

Usually escaped newlines are important for formatting program output.
Check fails if the number of ``\\n`` literals in translation do not match the source.

.. _check-end-colon:

Mismatched colon
~~~~~~~~~~~~~~~~

*Source and translation do not both end with a colon*

Checks that colons are replicated between both source and translation. The
presence of colons is also checked for various languages where they do not
belong (Chinese or Japanese).

.. seealso::

   `Colon on Wikipedia <https://en.wikipedia.org/wiki/Colon_(punctuation)>`_

.. _check-end-ellipsis:

Mismatched ellipsis
~~~~~~~~~~~~~~~~~~~

*Source and translation do not both end with an ellipsis*

Checks that trailing ellipses are replicated between both source and translation.
This only checks for real ellipsis (``…``) not for three dots (``...``).

An ellipsis is usually rendered nicer than three dots in print, and sounds better with text-to-speech.

.. seealso::

   `Ellipsis on Wikipedia <https://en.wikipedia.org/wiki/Ellipsis>`_


.. _check-end-exclamation:

Mismatched exclamation mark
~~~~~~~~~~~~~~~~~~~~~~~~~~~

*Source and translation do not both end with an exclamation mark*

Checks that exclamations are replicated between both source and translation.
The presence of exclamation marks is also checked for various languages where
they do not belong (Chinese, Japanese, Korean, Armenian, Limbu, Myanmar or
Nko).

.. seealso::

   `Exclamation mark on Wikipedia <https://en.wikipedia.org/wiki/Exclamation_mark>`_

.. _check-end-stop:

Mismatched full stop
~~~~~~~~~~~~~~~~~~~~

*Source and translation do not both end with a full stop*

Checks that full stops are replicated between both source and translation.
The presence of full stops is checked for various languages where they do not belong
(Chinese, Japanese, Devanagari or Urdu).

.. seealso::

   `Full stop on Wikipedia <https://en.wikipedia.org/wiki/Full_stop>`_

.. _check-end-question:

Mismatched question mark
~~~~~~~~~~~~~~~~~~~~~~~~

*Source and translation do not both end with a question mark*

Checks that question marks are replicated between both source and translation.
The presence of question marks is also checked for various languages where they
do not belong (Armenian, Arabic, Chinese, Korean, Japanese, Ethiopic, Vai or
Coptic).

.. seealso::

   `Question mark on Wikipedia <https://en.wikipedia.org/wiki/Question_mark>`_

.. _check-end-semicolon:

Mismatched semicolon
~~~~~~~~~~~~~~~~~~~~

*Source and translation do not both end with a semicolon*

Checks that semicolons at the end of sentences are replicated between both source and translation.
This can be useful to keep formatting of entries such as desktop files.

.. seealso::

   `Semicolon on Wikipedia <https://en.wikipedia.org/wiki/Semicolon>`_

.. _check-newline-count:

Mismatching line breaks
~~~~~~~~~~~~~~~~~~~~~~~

*Number of new lines in translation does not match source*

Usually newlines are important for formatting program output.
Check fails if the number of ``\n`` literals in translation do not match the source.


.. _check-plurals:

Missing plurals
~~~~~~~~~~~~~~~

*Some plural forms are not translated*

Checks that all plural forms of a source string have been translated.
Specifics on how each plural form is used can be found in the string definition.

Failing to fill in plural forms will in some cases lead to displaying nothing when
the plural form is in use.

.. _check-placeholders:

Placeholders
~~~~~~~~~~~~

*Translation is missing some placeholders:*

.. versionadded:: 3.9

Translation is missing some placeholders. These are either extracted from the
translation file or defined manually using ``placeholders`` flag, more can be
separated with colon, strings with space can be quoted:

.. code-block:: text

   placeholders:$URL$:$TARGET$:"some long text"

.. seealso::

   :ref:`custom-checks`

.. _check-punctuation-spacing:

Punctuation spacing
~~~~~~~~~~~~~~~~~~~

*Missing non breakable space before double punctuation sign*

.. versionadded:: 3.9

Checks that there is non breakable space before double punctuation sign
(exclamation mark, question mark, semicolon and colon). This rule is used only
in a few selected languages like French or Breton, where space before double
punctuation sign is a typographic rule.

.. seealso::

   `French and English spacing on Wikipedia <https://en.wikipedia.org/wiki/History_of_sentence_spacing#French_and_English_spacing>`_


.. _check-regex:

Regular expression
~~~~~~~~~~~~~~~~~~

*Translation does not match regular expression:*

.. versionadded:: 3.9

Translation does not match regular expression. The expression is either extracted from the
translation file or defined manually using ``regex`` flag:

.. code-block:: text

   regex:^foo|bar$



.. _check-same-plurals:

Same plurals
~~~~~~~~~~~~

*Some plural forms are translated in the same way*

Check that fails if some plural forms are duplicated in the translation.
In most languages they have to be different.

.. _check-begin-newline:

Starting newline
~~~~~~~~~~~~~~~~

*Source and translation do not both start with a newline*

Newlines usually appear in source strings for good reason, omissions or additions
can lead to formatting problems when the translated text is put to use.

.. seealso::

   :ref:`check-end-newline`

.. _check-begin-space:

Starting spaces
~~~~~~~~~~~~~~~

*Source and translation do not both start with same number of spaces*

A space in the beginning of a string is usually used for indentation in the interface and thus
important to keep.

.. _check-end-newline:

Trailing newline
~~~~~~~~~~~~~~~~

*Source and translation do not both end with a newline*

Newlines usually appear in source strings for good reason, omissions or additions
can lead to formatting problems when the translated text is put to use.

.. seealso::

   :ref:`check-begin-newline`

.. _check-end-space:

Trailing space
~~~~~~~~~~~~~~

*Source and translation do not both end with a space*

Checks that trailing spaces are replicated between both source and translation.

Trailing space is usually utilized to space out neighbouring elements, so
removing it might break layout.

.. _check-same:

Unchanged translation
~~~~~~~~~~~~~~~~~~~~~

*Source and translation are identical*

Happens if the source and corresponding translation strings is identical, down to
at least one of the plural forms. Some strings commonly found across all
languages are ignored, and various markup is stripped. This reduces
the number of false positives.

This check can help find strings mistakenly untranslated.

The default behavior of this check is to exclude words from the built-in
blacklist from the checking. These are words which are frequently not being
translated. This is useful to avoid false positives on short strings, which
consist only of single word which is same in several languages. This blacklist
can be disabled by adding ``strict-same`` flag to string or component.

.. seealso::

   :ref:`component`,
   :ref:`custom-checks`

.. _check-safe-html:

Unsafe HTML
~~~~~~~~~~~

*The translation uses unsafe HTML markup*

.. versionadded:: 3.9

The translation uses unsafe HTML markup. This check has to be enabled using
``safe-html`` flag (see :ref:`custom-checks`). There is also accompanied
autofixer which can automatically sanitize the markup.

.. seealso::

   The HTML check is performed by the `Bleach <https://bleach.readthedocs.io/>`_
   library developed by Mozilla.



.. _check-url:

URL
~~~

*The translation does not contain an URL*

.. versionadded:: 3.5

The translation does not contain an URL. This is triggered only in case the
unit is marked as containing URL. In that case the translation has to be a
valid URL.

.. _check-xml-tags:

XML markup
~~~~~~~~~~

*XML tags in translation do not match source*

This usually means the resulting output will look different. In most cases this is
not a desired result from changing the translation, but occasionally it is.

Checks that XML tags are replicated between both source and translation.



.. _check-xml-invalid:

XML syntax
~~~~~~~~~~

*The translation is not valid XML*

.. versionadded:: 2.8

The XML markup is not valid.

.. _check-zero-width-space:

Zero-width space
~~~~~~~~~~~~~~~~

*Translation contains extra zero-width space character*

Zero-width space (<U+200B>) characters are used to break messages within words (word wrapping).

As they are usually inserted by mistake, this check is triggered once they are present
in translation. Some programs might have problems when this character is used.

.. seealso::

    `Zero width space on Wikipedia <https://en.wikipedia.org/wiki/Zero-width_space>`_



Source checks
-------------

Source checks can help developers improve the quality of source strings.

.. _check-ellipsis:

Ellipsis
~~~~~~~~

*The string uses three dots (...) instead of an ellipsis character (…)*

This fails when the string uses three dots (``...``) when it should use an ellipsis character (``…``).

Using the Unicode character is in most cases the better approach and looks better
rendered, and may sound better with text-to-speech.

.. seealso::

   `Ellipsis on Wikipedia <https://en.wikipedia.org/wiki/Ellipsis>`_


.. _check-long-untranslated:

Long untranslated
~~~~~~~~~~~~~~~~~

*The string has not been translated for a long time*

.. versionadded:: 4.1

When the string has not been translated for a long time, it is can indicate problem in a
source string making it hard to translate.


.. _check-multiple-failures:

Multiple failing checks
~~~~~~~~~~~~~~~~~~~~~~~

*The translations in several languages have failing checks*

Numerous translations of this string have failing quality checks. This is
usually an indication that something could be done to improve the source
string.

This check failing can quite often be caused by a missing full stop at the end of
a sentence, or similar minor issues which translators tend to fix in
translation, while it would be better to fix it in the source string.

.. _check-unnamed-format:

Multiple unnamed variables
~~~~~~~~~~~~~~~~~~~~~~~~~~

*There are multiple unnamed variables in the string, making it impossible for
translators to reorder them*

.. versionadded:: 4.1

There are multiple unnamed variables in the string, making it impossible for
translators to reorder them.

Consider using named variables instead to allow translators to reorder them.

.. _check-optional-plural:

Unpluralised
~~~~~~~~~~~~

*The string is used as plural, but not using plural forms*

The string is used as a plural, but does not use plural forms. In case your
translation system supports this, you should use the plural aware variant of
it.

For example with Gettext in Python it could be:

.. code-block:: python

    from gettext import ngettext

    print ngettext('Selected %d file', 'Selected %d files', files) % files
