Number Formatting & Parsing Cheatsheet

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Formatting numbers

Localize.Number.to_string(1234567.89)
#=> {:ok, "1,234,567.89"}

Locale-specific decimal formatting

Locale1234567.89Grouping style
:en"1,234,567.89"Western (groups of 3)
:de"1.234.567,89"Period grouping, comma decimal
:ja"1,234,567.89"Western (same as English)
:hi"12,34,567.89"Indian (lakhs/crores)
:fr"1 234 567,89"Thin-space grouping, comma decimal

Currency formatting

Localize.Number.to_string(1234.56, currency: :USD, locale: :en)
#=> {:ok, "$1,234.56"}

Localize.Number.to_string(1234.56, currency: :EUR, locale: :de)
#=> {:ok, "1.234,56 €"}

Localize.Number.to_string(1234, currency: :JPY, locale: :ja)
#=> {:ok, "￥1,234"}

Accounting format (negative in parentheses)

Localize.Number.to_string(1234.56, format: :accounting, currency: :USD)
#=> {:ok, "$1,234.56"}

Localize.Number.to_string(-1234.56, format: :accounting, currency: :USD)
#=> {:ok, "($1,234.56)"}

Percentage

Localize.Number.to_string(0.456, format: :percent, locale: :en)
#=> {:ok, "46%"}

Localize.Number.to_string(0.456, format: :percent, locale: :de)
#=> {:ok, "46 %"}

Scientific notation

Localize.Number.to_string(1234567.89, format: :scientific)
#=> {:ok, "1.23456789E6"}

Compact / short formats

Localize.Number.to_string(1234567, format: :decimal_short)
#=> {:ok, "1M"}

Localize.Number.to_string(1234567890, format: :decimal_short)
#=> {:ok, "1B"}

Localize.Number.to_string(1234567, format: :decimal_long)
#=> {:ok, "1 million"}

Localize.Number.to_string(1234567, format: :currency_short, currency: :USD)
#=> {:ok, "$1M"}

Fractional digit control

Localize.Number.to_string(42, fractional_digits: 2)
#=> {:ok, "42.00"}

Localize.Number.to_string(3.14159, max_fractional_digits: 2)
#=> {:ok, "3.14"}

Localize.Number.to_string(3.1, min_fractional_digits: 3)
#=> {:ok, "3.100"}

Number ranges

Localize.Number.to_range_string(3..5)
#=> {:ok, "3–5"}

Localize.Number.to_range_string(3, 5, locale: :de)
#=> {:ok, "3–5"}

Format options summary

OptionValuesDefaultDescription
:localeatom, string, LanguageTagLocalize.get_locale()Formatting locale
:format:standard, :percent, :scientific, :currency, :accounting, :decimal_short, :decimal_long, :currency_short, or a pattern string:standardNumber format style
:currencyISO 4217 atom (:USD, :EUR, etc.)nilCurrency code (auto-selects currency format)
:number_system:default, :native, :traditional, or a system name:defaultDigit system
:rounding_mode:half_even, :half_up, :down, :up, :ceiling, :floor:half_evenRounding mode
:fractional_digitsintegerfrom format patternSets both min and max fractional digits
:min_fractional_digitsintegerfrom format patternMinimum fractional digits (trailing zeros)
:max_fractional_digitsintegerfrom format patternMaximum fractional digits (rounds to fit)

Parsing numbers

Localize.Number.parse("1,234.56")
#=> {:ok, 1234.56}

Localize.Number.parse("1.234,56", locale: :de)
#=> {:ok, 1234.56}

Localize.Number.parse("-42.5")
#=> {:ok, -42.5}

Scanning for numbers in text

Localize.Number.scan("The price is $1,234.56 per unit")
#=> ["The price is $", 1234.56, " per unit"]

Pre-validated options (hot-loop performance)

# Validate once
{:ok, options} = Localize.Number.Format.Options.validate_options(0, locale: :en, currency: :USD)

# Reuse for many calls — skips per-call option resolution
{:ok, _} = Localize.Number.to_string(1234.56, options)
{:ok, _} = Localize.Number.to_string(9876.54, options)