Currency converter

A utility class for handling money conversions between currencies. It uses a rate map defined relative to USD, lets you set an initial amount in one currency, and then convert that value into any other supported currency with consistent results.

Initialization

When you create a new instance of CurrencyConverter, you must pass in an array of exchange rates where each rate is defined relative to USD. In this array:

• USD is always the anchor with a value of 1.0.
• Every other entry defines how much 1 USD is worth in that currency

Example:

<?php

use Krystal\Text\CurrencyConverter;

// Initialize the converter with a set of rates
$converter = new CurrencyConverter([
    'USD' => 1.0,   // Base reference
    'EUR' => 0.95,  // 1 USD = 0.95 EUR
    'GBP' => 0.82,  // 1 USD = 0.82 GBP
    'JPY' => 136.5  // 1 USD = 136.5 JPY
]);

Now, the converter knows that 1 USD = 0.95 EUR and 1 USD = 0.82 GBP.

Set base

The set() method is how you define how much money you have in a specific currency and tell the converter which currency that amount is expressed in.

// Set the base amount in EUR
$converter->set(100, 'EUR');

By calling set($amount, $currency):

1. You tell the converter, for example, “I have 100 EUR.”

2. The converter converts this amount internally into the base reference value, using the rate of EUR.

3. Later, when you call convert($currency), it can accurately calculate how much your 100 EUR is worth in USD, GBP, JPY, etc.

Convert

The convert() method takes the base amount you previously set with set() (internally stored as a USD-equivalent value) and converts it into the target currency you request.

// Convert to USD
echo $converter->convert('USD'); // 105.26

// Convert to GBP
echo $converter->convert('GBP'); // 122.0

Check if a currency is available

The isAvailable() method checks whether a given currency code exists in the converter’s internal rate map (the array of rates you passed during initialization).

$isAvailable = $converter->isAvailable('JPY');

var_dump($isAvailable); // True