<?php
/**
 * 将十进制数字转换为二十六进制字母串
 */
function num2alpha($intNum, $isLower=true)
{
	$num26 = base_convert($intNum, 10, 26);
	$addcode = $isLower ? 49 : 17;
	$result = '';
	for ($i=0; $i<strlen($num26); $i++) {
		$code = ord($num26{$i});
		if ($code < 58) {
			$result .= chr($code+$addcode);
		} else {
			$result .= chr($code+$addcode-39);
		}
	}
	return $result;
}


/**
 * 将二十六进制字母串转换为十进制数字
 */
function alpha2num($strAlpha)
{
	if (ord($strAlpha{0}) > 90) {
		$startCode = 97;
		$reduceCode = 10;
	} else {
		$startCode = 65;
		$reduceCode = -22;
	}
	$num26 = '';
	for ($i=0; $i<strlen($strAlpha); $i++) {
		$code = ord($strAlpha{$i});
		if ($code < $startCode+10) {
			$num26 .= $code-$startCode;
		} else {
			$num26 .= chr($code-$reduceCode);
		}
	}
	return (int)base_convert($num26, 26, 10);
}