Regex: Check date is in YYYY-MM-DD format

[markl999]

To check a date is entered in YYYY-MM-DD format.

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if(preg_match('/^[0-9]{4}-[0-9]{2}-[0-9]{2}$/', $datein)){
    //it's ok
}else{
    //it's bad
}
 

This only checks the format and not the validity. E.g. 2003-09-31 will pass the check even though September doesn't have 31 days.

[jason]

A little extension to this.

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$datein = '1998-09-21';
if(preg_match('/^[0-9]{4}-(0[1-9]|1[0-2])-(0[1-9]|[1-2][0-9]|3[0-1])$/', $datein)){
    echo 'go';
}else{
    echo 'no go';
}

Makes sure things like 1998-13-32 won't get past and validate.

[evilMind]

alternative, with validation:

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function MyCheckDate( $postedDate ) {
   if ( ereg("^[0-9]{4}-[01][0-9]-[0-3][0-9]$",$postedDate) ) {
      list( $year , $month , $day ) = explode('-',$postedDate);
      return( checkdate( $month , $day , $year ) );
   } else {
      return( false );
   }
}
 

Check http://www.devnetwork.net/forums/viewtopic.php?t=13792&start=0&postdays=0&postorder=asc&highlight=
for a breakdown of the ereg

[jason]

Of course, anyone can simply replace the pregular expression from above with the ereg and get the same result with the function resulting in this:

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function MyCheckDate( $postedDate ) {
   if ( preg_match('/^[0-9]{4}-(0[1-9]|1[0-2])-(0[1-9]|[1-2][0-9]|3[0-1])$/', $postedDate) ) {
      list($year , $month , $day) = explode('-',$postedDate);
      return checkdate($month , $day , $year);
   } else {
      return false;
   }
}
 

[fastfingertips]

I'm using preg_match simply because faster then ereg.

Note: preg_match(), which uses a Perl-compatible regular expression syntax, is often a faster alternative to ereg().

[redmonkey]

Of course, anyone can simply replace the pregular expression from above with the ereg and get the same result with the function resulting in this:

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function MyCheckDate( $postedDate ) {
   if ( preg_match('/^[0-9]{4}-(0[1-9]|1[0-2])-(0[1-9]|[1-2][0-9]|3[0-1])$/', $postedDate) ) {
      list($year , $month , $day) = explode('-',$postedDate);
      return checkdate($month , $day , $year);
   } else {
      return false;
   }
}
 

Of course, the function could be simplified by removing the list/explode functions from the function resulting in this.

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function MyCheckDate( $postedDate ) {
   if (preg_match('/^(\d{4})-(\d{2})-(\d{2})$/', $postedDate, $datebit)) {
      return checkdate($datebit[2] , $datebit[3] , $datebit[1]);
   } else {
      return false;
   }
}
 

As the date validity is further checked against checkdate() then only simple pattern matching is required.

[volomike]

My version below checks if date is in MM/DD/YYYY format or MM-DD-YYYY format or MM DD YYYY format.

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public static function CheckValidDate($sDate) {
    $sDate = str_replace(' ', '-', $sDate);
    $sDate = str_replace('/', '-', $sDate);
    $sDate = str_replace('--', '-', $sDate);
    preg_match('/^(\d{2})-(\d{2})-(\d{4})$/', $sDate, $xadBits);
    return checkdate($xadBits[1], $xadBits[2], $xadBits[3]);
}
 

[matthijs]

What is $xadBits and were is it coming from? And what does checkdate look like?

[volomike]

What is $xadBits and were is it coming from? And what does checkdate look like?

$x- prefix means "byref", meaning I'm passing or receiving a value that will get updated without being returned as a result of a function.
-a- prefix means array
-d- prefix means date

So this translates to, "byref array of dates, broke up into bits". This is my Adapted Hungarian Notation because Hungarians are cool.

The PHP function returns that value to us -- we don't give it an initial value.

[syntia19]

Hi,
thank you, exactly what I'm looking for!

[Shirlee]

Thank you very much!