Get Exchange Rate For One Pair In One Direction

get_exchange_rate_for_one_pair.php

<?php
require 'exchange_rate.php';

function get_exr($_from=null, $_to=null) 
{
    $_res = null;
    $_pair = $_from.'_'.$_to;
    $_pairs = exchange_rate([ $_from => $_to ]);
    if(is_array($_pairs) && isset($_pairs[$_pair]))
    {
        $_res = $_pairs[$_pair];
    }
    return $_res;
}

echo get_exr('USD', 'TRY');