note 38719 added to function.mktime

function date_diff($date_from,$date_to) /* Calculates difference in days from date_from to date_to, taking into account leap years if date_from > date_to, the number of days is returned negative date_from and date_to format is: "dd-mm-yyyy" It can calculate ANY date difference, for example between 21-4-345 and 11-11-3412 This is possible by mapping any date to the "range 0" dates, as this table shows: INI END RANGE LEAP YEARS ... ... ... ... 01/01/1920 01/01/1939 -3 5 01/01/1940 01/01/1959 -2 5 01/01/1960 01/01/1979 -1 5 01/01/1980 01/01/1999 0 5 * this is the range used for calculations with mktime 01/01/2000 01/01/2019 1 5 01/01/2020 01/01/2039 2 5 01/01/2040 01/01/2059 3 5 01/01/2060 01/01/2079 4 5 ... ... ... ... */ { $date_from_parts = explode('-', $date_from); $date_to_parts = explode('-', $date_to); $day_from = $date_from_parts[0]; $mon_from = $date_from_parts[1]; $year_from = $date_from_parts[2]; $day_to = $date_to_parts[0]; $mon_to = $date_to_parts[1]; $year_to = $date_to_parts[2]; //if date_from is newer than date to, invert dates $sign=1; if ($year_from>$year_to) $sign=-1; else if ($year_from==$year_to) { if ($mon_from>$mon_to) $sign=-1; else if ($mon_from==$mon_to) if ($day_from>$day_to) $sign=-1; } if ($sign==-1) {//invert dates $day_from = $date_to_parts[0]; $mon_from = $date_to_parts[1]; $year_from = $date_to_parts[2]; $day_to = $date_from_parts[0]; $mon_to = $date_from_parts[1]; $year_to = $date_from_parts[2]; } $yearfrom1=$year_from; //actual years $yearto1=$year_to; //(yearfrom2 and yearto2 are used to calculate inside the range "0") //checks ini date if ($yearfrom1<1980) {//year is under range 0 $deltafrom=floor((1999-$yearfrom1)/20)*20; //delta t1 $yearfrom2=$yearfrom1+$deltafrom; //year used for calculations } else if($yearfrom1>1999) {//year is over range 0 $deltafrom=floor(($yearfrom1-1980)/20)*20; //delta t1 $yearfrom2=$yearfrom1-$deltafrom; //year used for calculations } else {//year is in range 0 $deltafrom=0; $yearfrom2=$yearfrom1; } //checks end date if ($yearto1<1980) {//year is under range 0 $deltato=floor((1999-$yearto1)/20)*20; //delta t2 $yearto2=$yearto1+$deltato; //year used for calculations } else if($yearto1>1999) {//year is over range 0 $deltato=floor(($yearto1-1980)/20)*20; //delta t2 $yearto2=$yearto1-$deltato; //year used for calculations } else {//year is in range 0 $deltato=0; $yearto2=$yearto1; } //Calculates the UNIX Timestamp for both dates (inside range 0) $ts_from = mktime(0, 0, 0, $mon_from, $day_from, $yearfrom2); $ts_to = mktime(0, 0, 0, $mon_to, $day_to, $yearto2); $diff = ($ts_to-$ts_from)/86400; //adjust ranges $diff += 7305 * (($deltafrom+$deltato) / 20); return $sign*$diff; } //I hope this can help //Any suggestion - comment - advise, feel free to e-mail me //web@nihongo.d2g.com - Leonardo Sasso ---- Manual Page -- http://www.php.net/manual/en/function.mktime.php Edit -- http://master.php.net/manage/user-notes.php?action=edit+38719 Delete -- http://master.php.net/manage/user-notes.php?action=delete+38719&report=yes Reject -- http://master.php.net/manage/user-notes.php?action=reject+38719&report=yes Search -- http://master.php.net/manage/user-notes.php