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# Number and Currency Formatting
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Access to device-specific number formatting preferences and regional currency information for proper localization of numeric data and monetary values.
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## Capabilities
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### Get Number Format Settings
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Retrieves the device's number formatting preferences, including decimal and grouping separators.
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```typescript { .api }
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/**
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 * Get device's number formatting settings
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 * @returns Object containing decimal and grouping separators
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 */
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function getNumberFormatSettings(): NumberFormatSettings;
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interface NumberFormatSettings {
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  /** Character used for decimal separation (e.g., ".", ",") */
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  decimalSeparator: string;
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  /** Character used for thousands grouping (e.g., ",", ".", " ") */
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  groupingSeparator: string;
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}
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```
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**Usage Examples:**
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```typescript
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import { getNumberFormatSettings } from "react-native-localize";
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const formatSettings = getNumberFormatSettings();
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console.log(formatSettings);
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// US: { decimalSeparator: ".", groupingSeparator: "," }
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// DE: { decimalSeparator: ",", groupingSeparator: "." }
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// FR: { decimalSeparator: ",", groupingSeparator: " " }
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// Format numbers according to device preferences
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function formatNumber(value: number): string {
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  const { decimalSeparator, groupingSeparator } = getNumberFormatSettings();
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  // Use native toLocaleString for proper formatting
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  return value.toLocaleString(undefined, {
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    minimumFractionDigits: 2,
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    maximumFractionDigits: 2
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  });
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}
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console.log(formatNumber(1234.56));
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// US: "1,234.56"
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// DE: "1.234,56"
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// FR: "1 234,56"
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```
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**Custom Number Formatting:**
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```typescript
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import { getNumberFormatSettings } from "react-native-localize";
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function formatCurrency(amount: number, currencyCode: string): string {
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  const { decimalSeparator, groupingSeparator } = getNumberFormatSettings();
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  // Manual formatting using device separators
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  const parts = Math.abs(amount).toFixed(2).split('.');
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  const integerPart = parts[0].replace(/\B(?=(\d{3})+(?!\d))/g, groupingSeparator);
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  const decimalPart = parts[1];
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  const formatted = `${integerPart}${decimalSeparator}${decimalPart}`;
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  const sign = amount < 0 ? '-' : '';
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  return `${sign}${currencyCode} ${formatted}`;
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}
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console.log(formatCurrency(1234.56, "USD"));
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// US: "USD 1,234.56"
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// DE: "USD 1.234,56"
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```
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### Get Device Currencies
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Gets an array of currencies associated with the device's locale preferences.
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```typescript { .api }
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/**
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 * Get currencies associated with device locales
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 * @returns Array of ISO currency codes (e.g., ["USD", "EUR"])
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 */
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function getCurrencies(): string[];
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```
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**Usage Examples:**
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```typescript
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import { getCurrencies, getCountry } from "react-native-localize";
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const currencies = getCurrencies();
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console.log(currencies); // ["USD", "EUR"]
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// Get primary currency
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const primaryCurrency = currencies[0];
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console.log(primaryCurrency); // "USD"
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// Use for currency selection
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function getDefaultCurrency(): string {
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  const currencies = getCurrencies();
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  return currencies[0] || "USD"; // fallback to USD
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}
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// Currency-aware price formatting
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function formatPrice(amount: number): string {
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  const currency = getDefaultCurrency();
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  return new Intl.NumberFormat(undefined, {
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    style: 'currency',
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    currency: currency
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  }).format(amount);
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}
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console.log(formatPrice(29.99));
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// US: "$29.99"
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// EU: "29,99 €"
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// UK: "£29.99"
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```
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**Multi-Currency Support:**
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```typescript
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import { getCurrencies, getCountry } from "react-native-localize";
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// App with multi-currency support
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function getSupportedCurrencies(): string[] {
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  const deviceCurrencies = getCurrencies();
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  const appSupportedCurrencies = ["USD", "EUR", "GBP", "JPY", "CAD"];
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  // Find intersection of device and app currencies
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  return deviceCurrencies.filter(currency => 
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    appSupportedCurrencies.includes(currency)
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  );
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}
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// Currency selection with fallback
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function selectBestCurrency(): string {
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  const supported = getSupportedCurrencies();
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  if (supported.length > 0) {
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    return supported[0];
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  }
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  // Fallback based on country
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  const country = getCountry();
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  const countryToCurrency = {
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    "US": "USD",
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    "GB": "GBP", 
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    "JP": "JPY",
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    "CA": "CAD"
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  };
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  return countryToCurrency[country] || "USD";
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}
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```
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**E-commerce Integration:**
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```typescript
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import { getCurrencies, getNumberFormatSettings } from "react-native-localize";
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class PriceFormatter {
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  private currency: string;
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  private formatSettings: NumberFormatSettings;
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  constructor() {
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    this.currency = getCurrencies()[0] || "USD";
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    this.formatSettings = getNumberFormatSettings();
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  }
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  formatPrice(amount: number, showCurrency: boolean = true): string {
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    const formatted = new Intl.NumberFormat(undefined, {
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      style: showCurrency ? 'currency' : 'decimal',
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      currency: this.currency,
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      minimumFractionDigits: 2,
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      maximumFractionDigits: 2
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    }).format(amount);
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    return formatted;
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  }
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  formatDiscount(original: number, discounted: number): string {
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    const savings = original - discounted;
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    const percentage = Math.round((savings / original) * 100);
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    return `Save ${this.formatPrice(savings)} (${percentage}%)`;
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  }
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}
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const formatter = new PriceFormatter();
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console.log(formatter.formatPrice(99.99)); // "$99.99" or "99,99 €"
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console.log(formatter.formatDiscount(99.99, 79.99)); // "Save $20.00 (20%)"
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```