Parse Date Format from Date String PHP

Question

I am trying to achieve this:

getFormat("Jan 2020") // returns: M Y
getFormat("01 Feb 2020") // returns: d M Y
getFormat("01-January-2020") // returns: d-F-Y

Idea is to basically reverse engineer the php date

This is what I've tried so far:

public function getFormat($date){
    $date = strtolower($date);
    $formats = array(
        "F" => array("january","february","march","april","may","june","july","august","september","october","november","december"),
        "M" => array("jan","feb","mar","apr","may","jun","jul","aug","sep","oct","nov","dec"),
    );

    foreach($formats as $format=>$data) {
        foreach($data as $d)
            if (stripos($date,$d) !== false) $date = str_replace($d,$format,$date);
    }
    return $date;
}

This would work for months or days but I don't think this technique would ever work for numeric values.

Are you wanting to use it for just date strings, or date/time strings as well? — Don't Panic
– Don't Panic, Commented Feb 27, 2020 at 22:16
So the strings will always have text as month? 12-12-12 is not possible I hope? — Andreas
– Andreas, Commented Feb 27, 2020 at 22:44

jspit · Accepted Answer · 2020-03-01 14:39:53Z

1

date_parse () checks whether day, month and year exist in the format. The parts are replaced with the format characters using regular expressions in the config array.

This is not a perfect solution. It is an approach that can be improved.

function getDateFormat($format){
    $parse = date_parse($format);
    if($parse['error_count']) return false;
    $conf = [
        '~\d{4}~' => ['year','Y'],
        '~[a-z]{4,8}~i' => ['month','F'],
        '~[a-z]{3}~i' => ['month','M'],
        '~(?<=[ /\-\.])\d{2}(?=[ /\-\.])~' => ['month','m'],
        '~\d{1,2}(?=[,])~' => ['day','j'],
        '~\d{2}~' => ['day','d'],
        '~\d{1}~' => ['day','j'],
    ];

    foreach($conf as $regEx => $types){
      if($parse[$types[0]] !== false) {
        $format = preg_replace($regEx, $types[1], $format, 1, $count);
        if($count) $parse[$types[0]] = false; ;
      }
    }
    return $format;

}

I haven't fully tested which expressions the function can handle correctly. Here are a few examples:

$data = [
  "Jan 2020","01 Feb 2020","01-January-2020",
  "2020-03-02","05.06.1987", "April 6, 1967",
  "1988", "5. July 1966", 
  "is a Error"

];
foreach($data as $format){
  $frm = getDateFormat($format);
  echo $format." : ".($frm ? $frm : "ERROR")."<br>";
}

Output:

Jan 2020 : M Y
01 Feb 2020 : d M Y
01-January-2020 : d-F-Y
2020-03-02 : Y-m-d
05.06.1987 : d.m.Y
April 6, 1967 : F j, Y
1988 : Y
5. July 1966 : j. F Y
is a Error : ERROR

edited Mar 1, 2020 at 14:39

answered Mar 1, 2020 at 13:47

jspit

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2 Comments

Andreas Over a year ago

I'll give it an upvote for good effort, but it doesn't solve it all. Such as April 16, 1967 will return F d, Y but it could be F j, Y we just don't know.

jspit Over a year ago

I added a regEx in case a comma follows the day. With a date template like April 16, 1967, it is not entirely clear to me whether the day should be output with j or d. Just like in your comment from 12.12.12, there are other cases that cannot be solved.

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