CodeIgniter helper to format numbers to Japanese currency, using the kanjis for thousand and ten thousand.

currency_helper.php

<?php if (!defined('BASEPATH')) exit('No direct script access allowed');

if ( ! function_exists('format_yen'))
{
	/**
	 * Returns a number in Japanese currency format
	 * @param float $value The number to be formated
	 * @param string $symbol_position Define if should use the pre or post aligned kanji
	 * @param string $decimal Define what to do with decimal part of number
	 * @return boolean|string Returns the formated number or FALSE in case of error.
	 */
	function format_yen($value = NULL, $symbol_position = 'pre', $decimal = 'ignore'){
		
		if(is_null($value))	return FALSE;
		
		if(!is_numeric($value)) return FALSE;
		
		$value = $decimal == 'ignore' ? floor($value) : round($value);
		
		if($value >= 10000)
		{
			$ten_thousand = substr($value, -4);
			$rest = substr($value, 0, -4) . '万';
			
			$value = $ten_thousand == '0000' ? $rest : $rest . $ten_thousand;  
		}

		if($value >= 1000)
		{
			$thousand = substr($value, -3);
			$rest = substr($value, 0, -3) . '千';
				
			$value = $thousand == '000' ? $rest  : $rest . $thousand;
		}
		
		return $symbol_position == 'pre' ? '&yen&nbsp' . $value : $value . '&nbsp円';
	}	
}