如何区分日期格式为dd / mm / yy或dd / mm / yyyy？

Question

I'm trying to access the format of a given date value. I need to check whether the format is in dd/mm/yy or dd/mm/yyyy . I have used the following patterns with preg_match() , but they do not work.

'^\d{1,2}\/\d{1,2}\/\d{4}^'  //  dd/mm/yyyy

'^\d{1,2}\/\d{1,2}\/\d{2}^'  //  dd/mm/yy

Can someone help me to find the correct pattern?

Answer 1

Problems:

1. This $ should be in end instead of ^ . $ is for end of string.

2. Don't forget delimiters / .

Regular expression:

/^\\d{1,2}\\/\\d{1,2}\\/\\d{4}$/ for strings like 10/10/1111

/^\\d{1,2}\\/\\d{1,2}\\/\\d{2}$/ for strings like 10/10/11

Try this code snippet here

Answer 2

You have an error in the syntax of your regular expression. In a regex, the start of the pattern is denoted by ^ while the end is by $.

You can use the following to validate the given date format.

$date_to_check = "22/06/2017";
$true = preg_match("/([0-9]{2})\/([0-9]{2})\/([0-9]{4})/", $date_to_check);
var_dump($true);

However, you shouldn't be validating a date against a regex expression only. You need to pass the Year, month, date to the php's checkdate() function to really validate it.

PHP checkdate() doc