# View Source Cldr.Number(Cldr Numbers v2.32.3)

Formats numbers and currencies based upon CLDR's decimal formats specification.

The format specification is documentated in Unicode TR35. There are several classes of formatting including non-scientific, scientific, rules based (for spelling and ordinal formats), compact formats that display `1k` rather than `1,000` and so on. See `Cldr.Number.to_string/2` for specific formatting options.

### Non-Scientific Notation Formatting

The following description applies to formats that do not use scientific notation or significant digits:

• If the number of actual integer digits exceeds the maximum integer digits, then only the least significant digits are shown. For example, 1997 is formatted as "97" if the maximum integer digits is set to 2.

• If the number of actual integer digits is less than the minimum integer digits, then leading zeros are added. For example, 1997 is formatted as "01997" if the minimum integer digits is set to 5.

• If the number of actual fraction digits exceeds the maximum fraction digits, then half-even rounding it performed to the maximum fraction digits. For example, 0.125 is formatted as "0.12" if the maximum fraction digits is 2. This behavior can be changed by specifying a rounding increment and a rounding mode.

• If the number of actual fraction digits is less than the minimum fraction digits, then trailing zeros are added. For example, 0.125 is formatted as "0.1250" if the minimum fraction digits is set to 4.

• Trailing fractional zeros are not displayed if they occur j positions after the decimal, where j is less than the maximum fraction digits. For example, 0.10004 is formatted as "0.1" if the maximum fraction digits is four or less.

### Scientific Notation Formatting

Numbers in scientific notation are expressed as the product of a mantissa and a power of ten, for example, 1234 can be expressed as 1.234 x 10^3. The mantissa is typically in the half-open interval [1.0, 10.0) or sometimes [0.0, 1.0), but it need not be. In a pattern, the exponent character immediately followed by one or more digit characters indicates scientific notation. Example: "0.###E0" formats the number 1234 as "1.234E3".

• The number of digit characters after the exponent character gives the minimum exponent digit count. There is no maximum. Negative exponents are formatted using the localized minus sign, not the prefix and suffix from the pattern. This allows patterns such as "0.###E0 m/s". To prefix positive exponents with a localized plus sign, specify '+' between the exponent and the digits: "0.###E+0" will produce formats "1E+1", "1E+0", "1E-1", and so on. (In localized patterns, use the localized plus sign rather than '+'.)

• The minimum number of integer digits is achieved by adjusting the exponent. Example: 0.00123 formatted with "00.###E0" yields "12.3E-4". This only happens if there is no maximum number of integer digits. If there is a maximum, then the minimum number of integer digits is fixed at one.

• The maximum number of integer digits, if present, specifies the exponent grouping. The most common use of this is to generate engineering notation, in which the exponent is a multiple of three, for example, "##0.###E0". The number 12345 is formatted using "##0.####E0" as "12.345E3".

• When using scientific notation, the formatter controls the digit counts using significant digits logic. The maximum number of significant digits limits the total number of integer and fraction digits that will be shown in the mantissa; it does not affect parsing. For example, 12345 formatted with "##0.##E0" is "12.3E3". Exponential patterns may not contain grouping separators.

### Significant Digits

There are two ways of controlling how many digits are shows: (a) significant digits counts, or (b) integer and fraction digit counts. Integer and fraction digit counts are described above. When a formatter is using significant digits counts, it uses however many integer and fraction digits are required to display the specified number of significant digits. It may ignore min/max integer/fraction digits, or it may use them to the extent possible.

# Summary

## Functions

Returns the metadata representing the given format.

Return the precision (number of digits) of a number

Formats a number and applies the `:approximately` format for a locale and number system.

Formats a number and applies the `:at_least` format for a locale and number system.

Formats a number and applies the `:at_most` format for a locale and number system.

Converts a number from the latin digits `0..9` into another number system. Returns `{:ok, string}` or `{:error, reason}`.

Converts a number from the latin digits `0..9` into another number system. Returns the converted number or raises an exception on error.

Formats the first and last numbers of a range and applies the `:range` format for a locale and number system.

Returns a number formatted into a string according to a format pattern and options.

Same as the execution of `to_string/2` but raises an exception if an error would be returned.

Return a valid number system from a provided locale and number system name or type.

# Types

Link to this type

# format_type()

View Source
```@type format_type() ::
:standard
| :decimal_short
| :decimal_long
| :currency_short
| :currency_long
| :percent
| :accounting
| :scientific
| :currency```

# Functions

Link to this function

# decimal_format_metadata(format, backend \\ default_backend())

View Source
```@spec decimal_format_metadata(String.t(), Cldr.backend()) ::
{:ok, Cldr.Number.Format.Meta.t()} | {:error, String.t()}```

Returns the metadata representing the given format.

Link to this function

# precision(number)

View Source

Return the precision (number of digits) of a number

This function delegates to `Cldr.Digits.number_of_digits/1`

## Example

``````iex> Cldr.Number.precision 1.234
4``````
Link to this function

# to_approx_string(number, backend \\ default_backend(), options \\ [])

View Source
```@spec to_approx_string(number() | Decimal.t(), Cldr.backend(), Keyword.t() | map()) ::
{:ok, String.t()} | {:error, {module(), String.t()}}```

Formats a number and applies the `:approximately` format for a locale and number system.

## Arguments

• `number` is an integer, float or Decimal to be formatted

• `backend` is any `Cldr` backend. That is, any module that contains `use Cldr`

• `options` is a keyword list defining how the number is to be formatted. See `Cldr.Number.to_string/3` for a description of the available options.

## Example

``````iex> Cldr.Number.to_approx_string 1234, TestBackend.Cldr
{:ok, "~1,234"}``````
Link to this function

# to_at_least_string(number, backend \\ default_backend(), options \\ [])

View Source
```@spec to_at_least_string(number() | Decimal.t(), Cldr.backend(), Keyword.t() | map()) ::
{:ok, String.t()} | {:error, {module(), String.t()}}```

Formats a number and applies the `:at_least` format for a locale and number system.

## Arguments

• `number` is an integer, float or Decimal to be formatted

• `backend` is any `Cldr` backend. That is, any module that contains `use Cldr`

• `options` is a keyword list defining how the number is to be formatted. See `Cldr.Number.to_string/3` for a description of the available options.

## Example

``````iex> Cldr.Number.to_at_least_string 1234, TestBackend.Cldr
{:ok, "1,234+"}``````
Link to this function

# to_at_most_string(number, backend \\ default_backend(), options \\ [])

View Source
```@spec to_at_most_string(number() | Decimal.t(), Cldr.backend(), Keyword.t() | map()) ::
{:ok, String.t()} | {:error, {module(), String.t()}}```

Formats a number and applies the `:at_most` format for a locale and number system.

## Arguments

• `number` is an integer, float or Decimal to be formatted

• `backend` is any `Cldr` backend. That is, any module that contains `use Cldr`

• `options` is a keyword list defining how the number is to be formatted. See `Cldr.Number.to_string/3` for a description of the available options.

## Example

``````iex> Cldr.Number.to_at_most_string 1234, TestBackend.Cldr
{:ok, "≤1,234"}``````
Link to this function

# to_number_system(number, system, backend \\ default_backend())

View Source
```@spec to_number_system(number(), atom(), Cldr.backend()) ::
String.t() | {:error, {module(), String.t()}}```

Converts a number from the latin digits `0..9` into another number system. Returns `{:ok, string}` or `{:error, reason}`.

## Examples

``````iex> Cldr.Number.to_number_system 123, :hant, TestBackend.Cldr
{:ok, "一百二十三"}

iex> Cldr.Number.to_number_system 123, :hebr, TestBackend.Cldr
{:ok, "קכ״ג"}``````
Link to this function

# to_number_system!(number, system, backend \\ default_backend())

View Source
`@spec to_number_system!(number(), atom(), Cldr.backend()) :: String.t() | no_return()`

Converts a number from the latin digits `0..9` into another number system. Returns the converted number or raises an exception on error.

## Example

``````iex> Cldr.Number.to_number_system! 123, :hant, TestBackend.Cldr
"一百二十三"``````
Link to this function

# to_range_string(number, backend \\ default_backend(), options \\ [])

View Source
```@spec to_range_string(Range.t(), Cldr.backend(), Keyword.t() | map()) ::
{:ok, String.t()} | {:error, {module(), String.t()}}```

Formats the first and last numbers of a range and applies the `:range` format for a locale and number system.

## Arguments

• `number` is an integer, float or Decimal to be formatted

• `backend` is any `Cldr` backend. That is, any module that contains `use Cldr`

• `options` is a keyword list defining how the number is to be formatted. See `Cldr.Number.to_string/3` for a description of the available options.

## Example

``````iex> Cldr.Number.to_range_string 1234..5678, TestBackend.Cldr
{:ok, "1,234–5,678"}``````
Link to this function

# to_string(number, backend \\ default_backend(), options \\ [])

View Source
```@spec to_string(
number() | Decimal.t() | String.t(),
Cldr.backend() | Keyword.t() | map(),
Keyword.t() | map()
) :: {:ok, String.t()} | {:error, {atom(), String.t()}}```

Returns a number formatted into a string according to a format pattern and options.

## Arguments

• `number` is an integer, float or Decimal to be formatted

• `backend` is any `Cldr` backend. That is, any module that contains `use Cldr`

• `options` is a keyword list defining how the number is to be formatted. The valid options are:

## Options

• `format`: the format style or a format string defining how the number is formatted. See `Cldr.Number.Format` for how format strings can be constructed. See `Cldr.Number.Format.format_styles_for/3` to return available format styles for a locale. The default `format` is `:standard`.

• If `:format` is set to `:long` or `:short` then the formatting depends on whether `:currency` is specified. If not specified then the number is formatted as `:decimal_long` or `:decimal_short`. If `:currency` is specified the number is formatted as `:currency_long` or `:currency_short` and `:fractional_digits` is set to 0 as a default.

• If `:format` is set to `:currency_long_with_symbol` then a format composed of `:currency_long` with the locale's currency format is used.

• `:format` may also be a format defined by CLDR's Rules Based Number Formats (RBNF). Further information is found in the module `Cldr.Rbnf`. The most commonly used formats in this category are to spell out the number in a the locales language. The applicable formats are `:spellout`, `:spellout_year`, `:ordinal`. A number can also be formatted as roman numbers by using the format `:roman` or `:roman_lower`.

• `currency`: is the currency for which the number is formatted. If `currency` is set and no `:format` is set, `:format` will be set to `:currency` as well. Currency may be any ISO 4217 currency code returned by `Cldr.Currency.known_currencies/0` or a ISO 24165 digital token identifier (crypto currency).

• `currency_symbol`: Allows overriding a currency symbol. The alternatives are:

• `:iso` the ISO currency code will be used instead of the default currency symbol.
• `:narrow` uses the narrow symbol defined for the locale. The same narrow symbol can be defined for more than one currency and therefore this should be used with care. If no narrow symbol is defined, the standard symbol is used.
• `:symbol` uses the standard symbol defined in CLDR. A symbol is unique for each currency and can be safely used.
• `:standard` (the default and recommended) uses the CLDR-defined symbol based upon the currency format for the locale.
• "string" uses `string` as the currency symbol
• `:cash`: a boolean which indicates whether a number being formatted as a `:currency` is to be considered a cash value or not. Currencies can be rounded differently depending on whether `:cash` is `true` or `false`. *This option is deprecated in favour of `currency_digits: :cash`. Ignored if the currency is a digital token.

• `:currency_digits` indicates which of the rounding and digits should be used. The options are `:accounting` which is the default, `:cash` or `:iso`. Ignored if the currency is a digital token.

• `:rounding_mode`: determines how a number is rounded to meet the precision of the format requested. The available rounding modes are `:down`, :half_up, :half_even, :ceiling, :floor, :half_down, :up. The default is `:half_even`.

• `:number_system`: determines which of the number systems for a locale should be used to define the separators and digits for the formatted number. If `number_system` is an `atom` then `number_system` is interpreted as a number system. See `Cldr.Number.System.number_systems_for/2`. If the `:number_system` is `binary` then it is interpreted as a number system name. See `Cldr.Number.System.number_system_names_for/2`. The default is `:default`.

• `:locale`: determines the locale in which the number is formatted. See `Cldr.known_locale_names/0`. The default is`Cldr.get_locale/0` which is the locale currently in affect for this `Process` and which is set by `Cldr.put_locale/1`.

• If `:fractional_digits` is set to a positive integer value then the number will be rounded to that number of digits and displayed accordingly - overriding settings that would be applied by default. For example, currencies have fractional digits defined reflecting each currencies minor unit. Setting `:fractional_digits` will override that setting.

• If `:maximum_integer_digits` is set to a positive integer value then the number is left truncated before formatting. For example if the number `1234` is formatted with the option `maximum_integer_digits: 2`, the number is truncated to `34` and formatted.

• If `:round_nearest` is set to a positive integer value then the number will be rounded to nearest increment of that value - overriding settings that would be applied by default.

• `:minimum_grouping_digits` overrides the CLDR definition of minimum grouping digits. For example in the locale `es` the number `1345` is formatted by default as `1345` because the locale defines the `minimium_grouping_digits` as `2`. If `minimum_grouping_digits: 1` is set as an option the number is formatted as `1.345`. The `:minimum_grouping_digits` is added to the grouping defined by the number format. If the sum of these two digits is greater than the number of digits in the integer (or fractional) part of the number then no grouping is performed.

• `:wrapper` is a 2-arity function that will be called for each number component with parameters `string` and `tag` where `tag` is one of `:number`, `:currency_symbol`, `:currency_space`, `:literal`, `:quote`, `:percent`, `:permille`, `:minus` or `:plus`. The function must return either a string or a Phoenix safe string such as that returned by `Phoenix.HTML.Tag.content_tag/3`. The function can be used to wrap format elements in HTML or other tags.

## Locale extensions affecting formatting

A locale identifier can specify options that affect number formatting. These options are:

• `nu`: defines the number system to be used if none is specified by the `:number_system` option to `to_string/2`

This key is part of the u extension and that document should be consulted for details on how to construct a locale identifier with these extensions.

## Wrapping format elements

Wrapping elements is particularly useful when formatting a number with a currency symbol and the requirement is to have different HTML formatting applied to the symbol than the number. For example:

``````iex> Cldr.Number.to_string(100, format: :currency, currency: :USD, wrapper: fn
...>   string, :currency_symbol -> "<span class=\"symbol\">" <> string <> "</span>"
...>   string, :number -> "<span class=\"number\">" <> string <> "</span>"
...>   string, :currency_space -> "<span>" <> string <> "</span>"
...>   string, _other -> string
...> end)
{:ok, "<span class=\"symbol\">\$</span><span class=\"number\">100.00</span>"}``````

It is also possible and recommended to use the `Phoenix.HTML.Tag.content_tag/3` function if wrapping HTML tags since these will ensure HTML entities are correctly encoded. For example:

``````iex> Cldr.Number.to_string(100, format: :currency, currency: :USD, wrapper: fn
...>   string, :currency_symbol -> Phoenix.HTML.Tag.content_tag(:span, string, class: "symbol")
...>   string, :number -> Phoenix.HTML.Tag.content_tag(:span, string, class: "number")
...>   string, :currency_space -> Phoenix.HTML.Tag.content_tag(:span, string)
...>   string, _other -> string
...> end)
{:ok, "<span class=\"symbol\">\$</span><span class=\"number\">100.00</span>"}``````

When formatting a number the format is parsed into format elements that might include a currency symbol, a literal string, inserted text between a currency symbol and the currency amount, a percent sign, the number itself and several other elements. In some cases it is helpful to be apply specific formatting to each element. This can be achieved by specifying a `:wrapper` option. This option takes a 2-arity function as an argument. For each element of the format the wrapper function is called with two parameters: the format element as a string and an atom representing the element type. The wrapper function is required to return a string that is then inserted in the final formatted number.

## Returns

• `{:ok, string}` or

• `{:error, {exception, message}}`

## Examples

``````iex> Cldr.Number.to_string 12345, TestBackend.Cldr
{:ok, "12,345"}

iex> Cldr.Number.to_string 12345, TestBackend.Cldr, locale: "fr"
{:ok, "12 345"}

iex> Cldr.Number.to_string 1345.32, TestBackend.Cldr, currency: :EUR, locale: "es", minimum_grouping_digits: 1
{:ok, "1.345,32 €"}

iex> Cldr.Number.to_string 1345.32, TestBackend.Cldr, currency: :EUR, locale: "es"
{:ok, "1345,32 €"}

iex> Cldr.Number.to_string 12345, TestBackend.Cldr, locale: "fr", currency: "USD"
{:ok, "12 345,00 \$US"}

iex> Cldr.Number.to_string 12345, TestBackend.Cldr, format: "#E0"
{:ok, "1.2345E4"}

iex> Cldr.Number.to_string 12345, TestBackend.Cldr, format: :accounting, currency: "THB"
{:ok, "THB 12,345.00"}

iex> Cldr.Number.to_string -12345, TestBackend.Cldr, format: :accounting, currency: "THB"
{:ok, "(THB 12,345.00)"}

iex> Cldr.Number.to_string 12345, TestBackend.Cldr, format: :accounting, currency: "THB",
...> locale: "th"
{:ok, "฿12,345.00"}

iex> Cldr.Number.to_string 12345, TestBackend.Cldr, format: :accounting, currency: "THB",
...> locale: "th", number_system: :native
{:ok, "฿๑๒,๓๔๕.๐๐"}

iex> Cldr.Number.to_string 1244.30, TestBackend.Cldr, format: :long
{:ok, "1 thousand"}

iex> Cldr.Number.to_string 1244.30, TestBackend.Cldr, format: :long, currency: "USD"
{:ok, "1,244 US dollars"}

iex> Cldr.Number.to_string 1244.30, TestBackend.Cldr, format: :short
{:ok, "1K"}

iex> Cldr.Number.to_string 1244.30, TestBackend.Cldr, format: :short, currency: "EUR"
{:ok, "€1K"}

iex> Cldr.Number.to_string 1234, TestBackend.Cldr, format: :spellout
{:ok, "one thousand two hundred thirty-four"}

iex> Cldr.Number.to_string 1234, TestBackend.Cldr, format: :spellout_verbose
{:ok, "one thousand two hundred and thirty-four"}

iex> Cldr.Number.to_string 1989, TestBackend.Cldr, format: :spellout_year
{:ok, "nineteen eighty-nine"}

iex> Cldr.Number.to_string 123, TestBackend.Cldr, format: :ordinal
{:ok, "123rd"}

iex> Cldr.Number.to_string 123, TestBackend.Cldr, format: :roman
{:ok, "CXXIII"}

iex> Cldr.Number.to_string 123, TestBackend.Cldr, locale: "th-u-nu-thai"
{:ok, "๑๒๓"}``````

## Errors

An error tuple `{:error, {exception, reason}}` will be returned if an error is detected. The two most likely causes of an error return are:

• A format cannot be compiled. In this case the error tuple will look like:
``````    iex> Cldr.Number.to_string(12345, TestBackend.Cldr, format: "0#")
{:error, {Cldr.FormatCompileError,
"Decimal format compiler: syntax error before: \"#\""}}``````
• The format style requested is not defined for the `locale` and `number_system`. This happens typically when the number system is `:algorithmic` rather than the more common `:numeric`. In this case the error return looks like:
``````    iex> Cldr.Number.to_string(1234, TestBackend.Cldr, locale: "he", number_system: "hebr", format: :percent)
{:error, {Cldr.UnknownFormatError,
"The locale :he with number system :hebr does not define a format :percent"}}``````
Link to this function

# to_string!(number, backend \\ default_backend(), options \\ [])

View Source
```@spec to_string!(
number() | Decimal.t() | String.t(),
Cldr.backend() | Keyword.t() | map(),
Keyword.t() | map()
) :: String.t() | no_return()```

Same as the execution of `to_string/2` but raises an exception if an error would be returned.

## Options

• `number` is an integer, float or Decimal to be formatted

• `options` is a keyword list defining how the number is to be formatted. See `Cldr.Number.to_string/2`

## Returns

• a formatted number as a string or

• raises an exception

## Examples

``````iex> Cldr.Number.to_string! 12345, TestBackend.Cldr
"12,345"

iex> Cldr.Number.to_string! 12345, TestBackend.Cldr, locale: "fr"
"12 345"``````
Link to this function

# validate_number_system(locale, number_system, backend \\ default_backend())

View Source
```@spec validate_number_system(
Cldr.Locale.locale_name() | Cldr.LanguageTag.t(),
Cldr.Number.System.system_name() | Cldr.Number.System.types(),
Cldr.backend()
) :: {:ok, Cldr.Number.System.system_name()} | {:error, {module(), String.t()}}```

Return a valid number system from a provided locale and number system name or type.

The number system or number system type must be valid for the given locale. If a number system type is provided, the underlying number system is returned.

## Examples

``````iex> Cldr.Number.validate_number_system :en, :latn, TestBackend.Cldr
{:ok, :latn}

iex> Cldr.Number.validate_number_system :en, :default, TestBackend.Cldr
{:ok, :latn}

iex> Cldr.Number.validate_number_system :en, :unknown, TestBackend.Cldr
{:error,
{Cldr.UnknownNumberSystemError, "The number system :unknown is unknown"}}

iex> Cldr.Number.validate_number_system "zz", :default, TestBackend.Cldr
{:error, {Cldr.InvalidLanguageError, "The language \"zz\" is invalid"}}``````