Correctly determine if date string is a valid date in that format

Question

I m receiving a date string from an API  and it is formatted as yyyy-mm-dd   I am currently using a regex to validate the string format  which works ok  but I can see some cases where it could be a correct format according to the string but actually an invalid date  i e  2013-13-01  for example   Is there a better way in PHP to take a string such as 2013-13-01 and tell if it is a valid date or not for the format yyyy-mm-dd

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Accordling with cl-sah s answer  but this sound better  shorter     function checkmydate  date       tempDate   explode  -    date     return checkdate  tempDate 1    tempDate 2    tempDate 0        Test  checkmydate  2015-12-01     true checkmydate  2015-14-04     false

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I m afraid that most voted solution  https   stackoverflow com a 19271434 3283279  is not working properly  The fourth test case  var dump validateDate  2012-2-25        false  is wrong  The date is correct  because it corresponds to the format - the m allows a month with or without leading zero  see  http   php net manual en datetime createfromformat php   Therefore a date 2012-2-25 is in format Y-m-d and the test case must be true not false   I believe that better solution is to test possible error as follows   function validateDate  date   format    Y-m-d         DateTime  createFromFormat  format   date        errors   DateTime  getLastErrors         return  errors  warning count       0  amp  amp   errors  error count       0

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You can use DateTime  createFromFormat   for this purpose  function validateDate  date   format    Y-m-d          d   DateTime  createFromFormat  format   date          The Y   4 digits year   returns TRUE for any integer with any number of digits so changing the comparison from    to     fixes the issue      return  d  amp  amp   d- gt format  format       date      Function taken from this answer  Also on php net  Originally written by Glavic    Test cases  var dump validateDate  2013-13-01         false var dump validateDate  20132-13-01        false var dump validateDate  2013-11-32         false var dump validateDate  2012-2-25          false var dump validateDate  2013-12-01         true var dump validateDate  1970-12-01         true var dump validateDate  2012-02-29         true var dump validateDate  2012    Y          true var dump validateDate  12012    Y         false  Demo

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The easiest way to check if given date is valid probably converting it to unixtime using strtotime  formatting it to the given date s format  then comparing it   function isValidDate  date        return date  Y-m-d   strtotime  date        date     Of course you can use regular expression to check for validness  but it will be limited to given format  every time you will have to edit it to satisfy another formats  and also it will be more than required  Built-in functions is the best way  in most cases  to achieve jobs

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Determine if any string is a date  function checkIsAValidDate  myDateString       return  bool strtotime  myDateString

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How about this one   We simply use a try-catch block     dateTime    an invalid datetime    try        dateTimeObject   new DateTime  dateTime     catch  Exception  exc        echo  Do something with an invalid DateTime       This approach is not limited to only one date time format  and you don t need to define any function

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Returns TRUE if the input parameter is a valid date string in  YYYY-MM-DD  format  aka  MySQL date format   The date separator can be only the  -  character                                                                                     function isMysqlDate  yyyymmdd        return checkdate substr  yyyymmdd  5  2   substr  yyyymmdd  8   substr  yyyymmdd  0  4             amp  amp   substr  yyyymmdd  4  1       -             amp  amp   substr  yyyymmdd  7  1       -

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Validate with checkdate function    date    2019-02-30     date parts   explode   -    date     if checkdate   date parts 1    date parts 2    date parts 0            date is valid  else        date is invalid

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Determine if string is a date  even if string is a non-standard format   strtotime doesn t accept any custom format    lt  php function validateDateTime  dateStr   format        date default timezone set  UTC         date   DateTime  createFromFormat  format   dateStr       return  date  amp  amp    date- gt format  format       dateStr         These return true validateDateTime  2001-03-10 17 16 18    Y-m-d H i s    validateDateTime  2001-03-10    Y-m-d    validateDateTime  2001    Y    validateDateTime  Mon    D    validateDateTime  March 10  2001  5 16 pm    F j  Y  g i a    validateDateTime  March 10  2001  5 16 pm    F j  Y  g i a    validateDateTime  03 10 01    m d y    validateDateTime  10  3  2001    j  n  Y    validateDateTime  20010310    Ymd    validateDateTime  05-16-18  10-03-01    h-i-s  j-m-y    validateDateTime  Monday 8th of August 2005 03 12 46 PM    l jS  of F Y h i s A    validateDateTime  Wed  25 Sep 2013 15 28 57    D  d M Y H i s    validateDateTime  17 03 18 is the time    H m s  i s  t h e  t i m e    validateDateTime  17 16 18    H i s        These return false validateDateTime  2001-03-10 17 16 18    Y-m-D H i s    validateDateTime  2001    m    validateDateTime  Mon    D-m-y    validateDateTime  Mon    D-m-y    validateDateTime  2001-13-04    Y-m-d

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Give this a try    date    2017-10-01     function date checker  input  devider      output   false      input   explode  devider   input      year    input 0      month    input 1      day    input 2      if  is numeric  year   amp  amp  is numeric  month   amp  amp  is numeric  day         if  strlen  year     4  amp  amp  strlen  month     2  amp  amp  strlen  day     2           output   true              return  output     if  date checker  date   -        echo  The function is working    else     echo  The function isNOT working

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You can also Parse the date for month date and year and then you can use the PHP function checkdate   which you can read about here  http   php net manual en function checkdate php  You can also try this one    date  2013-13-01    if  preg match     0-9  4 - 0 1-9  1 0-2  - 0 1-9   1-2  0-9  3 0-1       date                 echo  Date is valid        else          echo  Date is invalid

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This option is not only simple but also accepts almost any format  although with non-standard formats it can be buggy    timestamp   strtotime  date   return  timestamp    date   null

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Use in simple way with php prebuilt function   function checkmydate  date       tempDate   explode  -    date        checkdate month  day  year    return checkdate  tempDate 1    tempDate 2    tempDate 0        Test     checkmydate  2015-12-01      true    checkmydate  2015-14-04      false

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date check is a recursive function  it s need 3 argument      MONTH DAY YEAR                always valid date    this- gt date check  month  day  year        private function date check  month  day  year                checkdate   is a php function that check a date is valid          or not  if valid date it s return true else false                  status   checkdate  month  day  year            if  status    true                 always valid date    year    -     month    -     day               return  always valid date            else               day     day - 1                   recursive call                 return  this- gt date check  month  day  year

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Tested Regex solution       function isValidDate  date                    if  preg match         1 26  2 048  00   12  d  2468  048   13579  26  0 48   -    0 13578  1 02  - 0 1-9   12  d 3 01      0 469  11 - 0 1-9   12  d 30     02- 0 1-9   12  d         12  d  02468  1235679   13579  01345789      1 1345789  2 1235679  00  -    0 13578  1 02  - 0 1-9   12  d 3 01      0 469  11 - 0 1-9   12  d 30     02- 0 1-9  1 d 2 0-8            date                         return  date                            return null          This will return null if the date is invalid or is not yyyy-mm-dd format  otherwise it will return the date

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I have this thing that  even with PHP  I like to find functional solutions  So  for example  the answer given by  migli is really a good one  highly flexible and elegant   But it has a problem  what if you need to validate a lot of DateTime strings with the same format  You would have to repeat the format all over the place  what goes against the DRY principle  We could put the format in a constant  but still  we would have to pass the constant as an argument to every function call   But fear no more  We can use currying to our rescue  PHP doesn t make this task pleasant  but it s still possible to implement currying with PHP    lt  php function validateDateTime  format        return function  dateStr  use   format             date   DateTime  createFromFormat  format   dateStr           return  date  amp  amp   date- gt format  format       dateStr             So  what we just did  Basically we wrapped the function body in an anonymous and returned such function instead  We can call the validation function like this   validateDateTime  Y-m-d H i s    2017-02-06 17 07 11       true   Yeah  not a big difference    but the real power comes from the partially applied function  made possible by currying      Get a partially applied function  validate   validateDateTime  Y-m-d H i s        Now you can use it everywhere  without repeating the format   validate  2017-02-06 17 09 31       true  validate  1999-03-31 07 07 07       true  validate  13-2-4 3 2 45       false   Functional programming FTW

[php] Correctly determine if date string is a valid date in that format

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