php生成excel列名，超过26列大于Z问题解决办法

public static function stringFromColumnIndex($pColumnIndex = 0)
{
// Using a lookup cache adds a slight memory overhead, but boosts speed
// caching using a static within the method is faster than a class static,
// though it's additional memory overhead
static $_indexCache = array();

if (!isset($_indexCache[$pColumnIndex])) {
// Determine column string
if ($pColumnIndex $_indexCache[$pColumnIndex] = chr(65 + $pColumnIndex);
} elseif ($pColumnIndex $_indexCache[$pColumnIndex] = chr(64 + ($pColumnIndex / 26)) .
chr(65 + $pColumnIndex % 26);
} else {
$_indexCache[$pColumnIndex] = chr(64 + (($pColumnIndex - 26) / 676)) .
chr(65 + ((($pColumnIndex - 26) % 676) / 26)) .
chr(65 + $pColumnIndex % 26);
}
}
return $_indexCache[$pColumnIndex];
}

PHPExcel_Cell::stringFromColumnIndex($i); // 从o开始

PHPExcel_Cell::columnIndexFromString(‘AA’);