This Tech Tip is an implementation of the php function 'checkdate' which is used to validate a Gregorian date. The 'checkdate' function checks the validity of the date formed by the arguments and considers a date valid if each parameter is properly defined and within their expected range taking leap years into consideration.

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The general syntax for the PHP function is:

bool checkdate ( int $month , int $day , int $year )

Each of the parameters for the 'checkdate' function are integer values while the return value of the function is a boolean.

Parameters:

• $month (integer value)
  
  • The month is between 1 and 12 inclusive.
• $day (integer value)
  
  • The day is within the allowed number of days for the given month. Leap years are taken into consideration.
• $year (integer value)
  
  • The year is between 1 and 32767 inclusive.

Return:

• Boolean
  • Returns TRUE if the date given is valid; otherwise returns FALSE.

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Using the 'checkdate' function from 4D with the PHP Execute command.

The following method demonstrates an implementation of the PHP function 'checkdate' using the PHP Execute 4D command:

// php_checkdate // C_DATE($1) := 4D Date Var // C_BOOLEAN($0) := returns True if valid Gregorian date // Usage: $valid_b:=php_checkdate(!11/31/2011!) C_DATE($1;$date_d) C_INTEGER($month;$day;$year) C_BOOLEAN($0;$output;$phpOK) If (Count parameters=1)    $date_d:=$1    $month:=Month of($date_d)    $day:=Day of($date_d)    $year:=Year of($date_d)    $phpOK:=PHP Execute("";"checkdate";$output;$month;$day;$year)    $0:=$output Else     // no input date given so it cannot be valid    $0:=False End if

If the method above is saved in your database as a project method named php_checkdate then it can be used like this:

Example 1:

// use case #1 C_BOOLEAN($bool) C_DATE($date) $date:=!00/00/0000! $bool:=php_checkdate ($date) ALERT("is "+String($date)+" valid?\r\n"+String($bool))

Example 2:

// use case #2 C_BOOLEAN($bool) C_DATE($date) $date:=!02/02/2002! $bool:=php_checkdate ($date) ALERT("is "+String($date)+" valid?\r\n"+String($bool))

Example 3:

// making some assertions first to confirm it is working ASSERT(php_checkdate (!01/01/2001!);"01/01/01 is a valid date") ASSERT(php_checkdate (!12/31/2011!);"12/31/11 is a valid date") ASSERT(Not(php_checkdate (!00/00/0000!));"0/0/0 is NOT a valid date")