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I need to convert string value "290416" which is actually date but not in correct format. I need to change it in date format like 29/04/16. please help.
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If you don't need it as a date but only in date format. Meaning you are not performing any date-functions on it but just displaying it as a date you could use
$str = '290416';
$arr = str_split($str, 2);
$date_string = $implode('/', $arr);
The most robust way will be to use createFromFormat, passing in your format and the string, and they you have a DateTime object and can do many things with it.
define('MY_DATE_INPUT_FORMAT', 'mdy');
define('MY_DATE_OUTPUT_FORMAT', 'm/d/y');
$inputDateString = '042916';
$dateObj = DateTime::createFromFormat(MY_DATE_INPUT_FORMAT, $inputDateString);
$outputString = $dateObj->format(MY_DATE_OUTPUT_FORMAT);
This can also be done procedurally:
$date = date_create_from_format(MY_DATE_INPUT_FORMAT, $inputDateString);
echo date_format($date, MY_DATE_OUTPUT_FORMAT);