iliaal/php_excel — pull request #90 by johmue (2014-08-16 00:58:33+00:00)
Title: added default date format when writing dates

$sheet->write(1, 1, $timestamp, null, ExcelFormat::AS_DATE)

Before change:
$sheet->isDate(1, 1); --> false (format was missing and therefore is a normal number)

After change:
$sheet->isDate(1, 1); --> true