6.22 locale -- Internationalization services
Keywords: lib

# 6.22 `locale` -- Internationalization services

The `locale` module opens access to the POSIX locale database and functionality. The POSIX locale mechanism allows programmers to deal with certain cultural issues in an application, without requiring the programmer to know all the specifics of each country where the software is executed.

The `locale` module is implemented on top of the `_locale` module, which in turn uses an ANSI C locale implementation if available.

The `locale` module defines the following exception and functions:

`setlocale` (category[, value])
  If value is specified, modifies the locale setting for the category. The available categories are listed in the data description below. The value is the name of a locale. An empty string specifies the user's default settings. If the modification of the locale fails, the exception `Error` is raised. If successful, the new locale setting is returned.

  If no value is specified, the current setting for the category is returned.

  `setlocale()` is not thread safe on most systems. Applications typically start with a call of

        import locale
        locale.setlocale(locale.LC_ALL,"")

  This sets the locale for all categories to the user's default setting (typically specified in the $LANG environment variable). If the locale is not changed thereafter, using multithreading should not cause problems.

`Error`
  Exception raised when `setlocale()` fails.

`localeconv` ()
  Returns the database of of the local conventions as a dictionary. This dictionary has the following strings as keys:
  - `decimal_point` specifies the decimal point used in floating point number representations for the `LC_NUMERIC` category.
  - `grouping` is a sequence of numbers specifying at which relative positions the `thousands_sep` is expected. If the sequence is terminated with `CHAR_MAX`, no further grouping is performed. If the sequence terminates with a `0`, the last group size is repeatedly used.
  - `thousands_sep` is the character used between groups.
  - `int_curr_symbol` specifies the international currency symbol from the `LC_MONETARY` category.
  - `currency_symbol` is the local currency symbol.
  - `mon_decimal_point` is the decimal point used in monetary values.
  - `mon_thousands_sep` is the separator for grouping of monetary values.
  - `mon_grouping` has the same format as the `grouping` key; it is used for monetary values.
  - `positive_sign` and `negative_sign` gives the sign used for positive and negative monetary quantities.
  - `int_frac_digits` and `frac_digits` specify the number of fractional digits used in the international and local formatting of monetary values.
  - `p_cs_precedes` and `n_cs_precedes` specifies whether the currency symbol precedes the value for positive or negative values.
  - `p_sep_by_space` and `n_sep_by_space` specifies whether there is a space between the positive or negative value and the currency symbol.
  - `p_sign_posn` and `n_sign_posn` indicate how the sign should be placed for positive and negative monetary values.

  The possible values for `p_sign_posn` and `n_sign_posn` are given below.

  Value | Explanation
  --- | ---
  `0` | Currency and value are surrounded by parentheses.
  `1` | The sign should precede the value and currency symbol.
  `2` | The sign should follow the value and currency symbol.
  `3` | The sign should immediately precede the value.
  `4` | The sign should immediately follow the value.
  `LC_MAX` | Nothing is specified in this locale.

`strcoll` (string1,string2)
  Compares two strings according to the current `LC_COLLATE` setting. As any other compare function, returns a negative, or a positive value, or `0`, depending on whether string1 collates before or after string2 or is equal to it.

`strxfrm` (string)
  Transforms a string to one that can be used for the built-in function `cmp()`, and still returns locale-aware results. This function can be used when the same string is compared repeatedly, e.g. when collating a sequence of strings.

`format` (format, val, [grouping`= 0`])
  Formats a number val according to the current `LC_NUMERIC` setting. The format follows the conventions of the `%` operator. For floating point values, the decimal point is modified if appropriate. If grouping is true, also takes the grouping into account.

`str` (float)
  Formats a floating point number using the same format as the built-in function `str(float)`, but takes the decimal point into account.

`atof` (string)
  Converts a string to a floating point number, following the `LC_NUMERIC` settings.

`atoi` (string)
  Converts a string to an integer, following the `LC_NUMERIC` conventions.

`LC_CTYPE`
  Locale category for the character type functions. Depending on the settings of this category, the functions of module `string` dealing with case change their behaviour.

`LC_COLLATE`
  Locale category for sorting strings. The functions `strcoll()` and `strxfrm()` of the `locale` module are affected.

`LC_TIME`
  Locale category for the formatting of time. The function `time.strftime()` follows these conventions.

`LC_MONETARY`
  Locale category for formatting of monetary values. The available options are available from the `localeconv()` function.

`LC_MESSAGES`
  Locale category for message display. Python currently does not support application specific locale-aware messages. Messages displayed by the operating system, like those returned by `os.strerror()` might be affected by this category.

`LC_NUMERIC`
  Locale category for formatting numbers. The functions `format()`, `atoi()`, `atof()` and `str()` of the `locale` module are affected by that category. All other numeric formatting operations are not affected.

`LC_ALL`
  Combination of all locale settings. If this flag is used when the locale is changed, setting the locale for all categories is attempted. If that fails for any category, no category is changed at all. When the locale is retrieved using this flag, a string indicating the setting for all categories is returned. This string can be later used to restore the settings.

`CHAR_MAX`
  This is a symbolic constant used for different values returned by `localeconv()`.

Example:

      >>> import locale
      >>> loc = locale.setlocale(locale.LC_ALL) # get current locale
      >>> locale.setlocale(locale.LC_ALL, "de") # use German locale
      >>> locale.strcoll("f\344n", "foo") # compare a string containing an umlaut
      >>> locale.setlocale(locale.LC_ALL, "") # use user's preferred locale
      >>> locale.setlocale(locale.LC_ALL, "C") # use default (C) locale
      >>> locale.setlocale(locale.LC_ALL, loc) # restore saved locale

Subsections

- 6.22.1 Background, details, hints, tips and caveats
- 6.22.2 For extension writers and programs that embed Python