Call to undefined function strptime()

// **************** vytvoreni unixtimestamp ************************
// **************** pouzito pro cas checkin ************************
$in = $od;                                   // zjisteni data prijezdu
// **************** prepis data do formatu %Y%m%d%H%M%S ************
$beforein = $in;                                
$afterin = preg_replace("/([0-9]{2}).([0-9]{2}).([0-9]{4})/", "$3$2$1", $beforein)."140000";
// *****************************************************************
$datumin = $afterin;                                       // zapis data prijezdu do promenne
$informatin = '%Y%m%d%H%M%S';                              // vstupni format pro vytvoreni unixtimestamp
$outformatin =  '%A, %d %B %Y %T %Z';                      // vystupni format funkce strftime
$ftimein = strptime($datumin,$informatin);                 // promena $ftime dostane informace o datu a case
$unxTimestampin = mktime(                                  // vytvoreni unixoveho razitka
                        $ftimein['tm_hour'],
                        $ftimein['tm_min'],
                        $ftimein['tm_sec'],
                        1 ,
                        $ftimein['tm_yday'] + 1,
                        $ftimein['tm_year'] + 1900
                      );
// echo strftime($outformat , $unxTimestamp );       // vystup data a casu ve vystupnim formatu

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