Function Looping Issue

I needed a function which I could pass a date and a number N, which would be any given number of working days. Back out of the function I wanted the unix date stap of the 15th working day since the input date.

I found what I needed on php.net - but didn't understand how to use it. In fact, I don't know what &$t does, the ampersand part of that.

The comlete function I based mine on is here:

/*
$date - date (dd/mm/yyyy)
$n - number of days
$t - resulting timestamp
*/

function getNthWorkingDay($date,$n,&$t)
{
   $arr = array();
   list($day,$month,$year) = explode("/",$date);

   $ts = mktime(0,0,0,$month,$day,$year);

   for($i = 1; $i <= $n; $i++)
   {
       $_ts = mktime(0,0,0,$month,$day + $i,$year);
       $arr[$i - 1]["d"] = date("w",$_ts);
       $arr[$i - 1]["ts"] = $_ts;
   }

   $working_days = array();
   $j = 0;

   for($i = 1; $i <= $n; $i++)
   {
       if($arr[$i - 1]["d"] != 6 AND $arr[$i - 1]["d"] != 0)
       {
           $working_days[$j]["d"] = $arr[$i - 1]["d"];
           $working_days[$j]["ts"] = $arr[$i - 1]["ts"];
           $j++;
       }
   }

   if(sizeOf($working_days) >= $n)
   {
       $t = $working_days[sizeOf($working_days) - 1]["ts"];
   }
   else
   {
       $_n = $n - sizeOf($working_days);
      
       getNthWorkingDay(date("d/m/Y",$arr[$n-1]["ts"]),$_n,$t);
   }
}
?>

PHP:

So I hacked that into:

function tep_get_Nth_working_day($date,$n)
{
   $arr = array();

   $day = date("d", $date);
   $month = date("m", $date);
   $year = date("Y", $date);
   
   //echo '<br>' . $day . ' - ' . $month . ' - ' . $year;

   $ts = mktime(0,0,0,$month,$day,$year);

   for($i = 1; $i <= $n; $i++)
   {
       $_ts = mktime(0,0,0,$month,$day + $i,$year);
       $arr[$i - 1]["d"] = date("w",$_ts);
       $arr[$i - 1]["ts"] = $_ts;
   }

   $working_days = array();
   $j = 0;

   for($i = 1; $i <= $n; $i++)
   {
       if($arr[$i - 1]["d"] != 6 AND $arr[$i - 1]["d"] != 0)
       {
           $working_days[$j]["d"] = $arr[$i - 1]["d"];
           $working_days[$j]["ts"] = $arr[$i - 1]["ts"];
           $j++;
       }
   }
//echo '<br>' . $working_days[sizeOf($working_days) - 1]["ts"];
   if(sizeOf($working_days) >= $n)
   {
   	   $x = sizeOf($working_days) - 1;
   	   $t = $working_days[$x]["ts"];
       
       //echo '<br>T:' . $t . ' and sizeof:' . sizeOf($working_days) - 1;
       
       //echo '<pre>';
   	   //print_r($working_days);
   	   //echo '</pre>';
       
   	   echo '<br>T: ' . $t;
   	   
       return $t;
   }
   else
   {
       $_n = $n - sizeOf($working_days);
      
       tep_get_Nth_working_day($arr[$n-1]["ts"],$_n);
   }
   
   

}

PHP:

Problem is... $t echoes just nicely but it never returns anything. Line 44 in this example actually give me what I want but I can't get it out of the function.

$unix_date_tim = 1140480000;
echo tep_get_Nth_working_day($unix_date_time, 15);

PHP:

Nothing...

It's probably due to the looping i.e. within the function it calls itself again.

What is that &$t? How do I get this function to trow me back $t instead of returning nothing?

 

I tried to re-include the &$t thing, whatever it may be, but keep getting "Only variables can be passed by reference in".

Considering the original function isn't even returning any value, how is it supposed to work?

 

in php 4 addin an anpersand & infront of a variable / objects

makes the variable be passed by reference not passed by value

its a hard concept to explain, have you ever heard of pointers (These are used extensively in C and C++)

passing by reference is more efficient but has some problems

in php5 they do away with this ampersand mess and al values are passed by reference

 

ok i pasted the code onto test file on my pc

can u paste where in php.net u got this code from i want to see the bigger picture

thats called recursion

below is the code i pasted into test.php

<?php
      function tep_get_Nth_working_day($date,$n)
  
      {
 
         $arr = array();
 
       

         $day = date("d", $date);
 
         $month = date("m", $date);
 
         $year = date("Y", $date);

         echo '<br>' . $day . ' - ' . $month . ' - ' . $year;

       
 
         $ts = mktime(0,0,0,$month,$day,$year);

       

         for($i = 1; $i <= $n; $i++)
 
         {
 
             $_ts = mktime(0,0,0,$month,$day + $i,$year);
 
             $arr[$i - 1]["d"] = date("w",$_ts);
 
             $arr[$i - 1]["ts"] = $_ts;

         }

         $working_days = array();
 
         $j = 0;

       

         for($i = 1; $i <= $n; $i++)
 
         {
 
             if($arr[$i - 1]["d"] != 6 AND $arr[$i - 1]["d"] != 0)

             {

                 $working_days[$j]["d"] = $arr[$i - 1]["d"];
 
                 $working_days[$j]["ts"] = $arr[$i - 1]["ts"];
 
                 $j++;
 
             }
 
         }
 
      echo '<br>' . $working_days[sizeOf($working_days) - 1]["ts"];
  
         if(sizeOf($working_days) >= $n)
 
         {
             $x = sizeOf($working_days) - 1;

             $t = $working_days[$x]["ts"];

             echo '<br>T:' . $t . ' and sizeof:' . sizeOf($working_days) - 1;

             echo '<pre>';

             print_r($working_days);

             echo '</pre>';


             echo '<br>T: ' . $t;

             return $t;

         }

         else
 
         {
 
             $_n = $n - sizeOf($working_days);

             tep_get_Nth_working_day($arr[$n-1]["ts"],$_n);

         }
         
         

      } 
      
      
 
      $unix_date_tim = 1140480000;

      echo tep_get_Nth_working_day($unix_date_time, 15); 
 ?>

PHP:

heres what output i got using PHP 5.1 and i run this script using php 4.4 as well with same result

01 - 01 - 1970
1292400
16 - 01 - 1970
1638000
20 - 01 - 1970
1810800-1

Array
(
    [0] => Array
        (
            [d] => 3
            [ts] => 1724400
        )

    [1] => Array
        (
            [d] => 4
            [ts] => 1810800
        )

)


T: 1810800

PHP:

 

You answered yourself in the question, it's passing by reference.

You can use the original example like this

getNthWorkingDay("12/05/06",15,$t);

print $t;

Code (markup):

Works for me..

 

wwm, got the function from here: http://uk.php.net/manual/en/function.date.php Search "working" on that page and it will jump straight down. The person who wrote didn;t supply an example.

Not how in your output, it doesn't do the last echo.

Forqueue, tried it and it worked!

Never knew it could work like that! So I basically tell te function, via the 3d argument, "I want your output back in a global variable called $t". Run the function (which doesn't use 'return') and just echo $t! Wow!

As simple as that... Quite amazed really.. The things you can learn when others are in the pub Thanks!

 

found the function on php.net

sometimes i wonder why do some people on php.net write the most obscure code ever!
without comments and examples either!

 

I even e-mailed the poor guy earlier today... Will probably be rather annoyed with such a n00b question

However, up until this guy, I had all my OS queries answered by the code providers when I sniffed out their e-mail address on the net and mailed them. As quick as just a few hours even. The after 'sales' service you sometimes get is astonishing, even better than some paid for software. Just goes to show... If you don't ask, you don't get.

Not that I'm some kind of selfish bastard. I helped people on osCommerce who turned out to be competitors! (Next time I'll ask what they sell first... Live and learn.)