Adding arrays

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  • dennis.sprengers@gmail.com
    #1

    Adding arrays

    Consider the following multi-dimensional array:
    ---------------------------
    $arr = array(
    array(3, 5, 7, 9),
    array(2, 4, 6, 8),
    array(1, 3, 5, 7)
    );

    function add_arrays($arr ) {
    for ($row = 0; $row < count($arr[0]); $row++) {
    for ($column = 0; $column < count($arr[$column]); $column++) {
    $totals[$row] = $totals[$row] + $arr[$column][$row];
    }
    }
    print_r($totals );
    }

    add_arrays($arr );
    ---------------------------
    This returns the following array:
    Array ( [0] =6 [1] =12 [2] =18 [3] =24 )

    These are the totals of the array's in $arr: 6 (3 + 2 + 1, added all
    first elements), 12 (5 + 4 + 3, added all second elements), etc. This
    took me quite a portion of the day to construct ;) However, I would
    like add_arrays to return a multidimensiona l array like this:

    Array (
    Array ( [0] =3 [1] = 5 [2] = 7 [3] = 9 ) // 1st row
    Array ( [0] =5 [1] = 9 [2] =13 [3] =17 ) // 1st row + second
    row (i.e. 5 = 3 + 2)
    Array ( [0] =6 [1] =12 [2] =18 [3] =24 ) // 1st _ 2nd + 3rd
    row (i.e. 6 = 3 + 2 + 1)
    )

    Could somebody please help me building a function that does just that?
    Adding one row to the previous one and adding the result to the output
    array? Any help would be greatly apprectiated!

    Tags: None
    • Daz
      #2
      Re: Adding arrays

      On May 7, 4:05 pm, dennis.spreng.. .@gmail.com wrote:
      Consider the following multi-dimensional array:
      ---------------------------
      $arr = array(
      array(3, 5, 7, 9),
      array(2, 4, 6, 8),
      array(1, 3, 5, 7)
      );
      >
      function add_arrays($arr ) {
      for ($row = 0; $row < count($arr[0]); $row++) {
      for ($column = 0; $column < count($arr[$column]); $column++) {
      $totals[$row] = $totals[$row] + $arr[$column][$row];
      }
      }
      print_r($totals );
      >
      }
      >
      add_arrays($arr );
      ---------------------------
      This returns the following array:
      Array ( [0] =6 [1] =12 [2] =18 [3] =24 )
      >
      These are the totals of the array's in $arr: 6 (3 + 2 + 1, added all
      first elements), 12 (5 + 4 + 3, added all second elements), etc. This
      took me quite a portion of the day to construct ;) However, I would
      like add_arrays to return a multidimensiona l array like this:
      >
      Array (
      Array ( [0] =3 [1] = 5 [2] = 7 [3] = 9 ) // 1st row
      Array ( [0] =5 [1] = 9 [2] =13 [3] =17 ) // 1st row + second
      row (i.e. 5 = 3 + 2)
      Array ( [0] =6 [1] =12 [2] =18 [3] =24 ) // 1st _ 2nd + 3rd
      row (i.e. 6 = 3 + 2 + 1)
      )
      >
      Could somebody please help me building a function that does just that?
      Adding one row to the previous one and adding the result to the output
      array? Any help would be greatly apprectiated!
      Is there any guarantee that the arrays will all be the same length as
      one-another? Are they always a set length, or can the lengths vary?

      Personally, I would start with making an empty array, which is the
      same length as the size of the longest array. Set all values in that
      array to 0. Then, loop through each array, and loop through the values
      of each array, and add them to the starting array. Now return the
      array you just created. Hope that makes sense. Example to follow.

        Comment

        • Daz
          #3
          Re: Adding arrays

          On May 7, 4:05 pm, dennis.spreng.. .@gmail.com wrote:
          Consider the following multi-dimensional array:
          ---------------------------
          $arr = array(
          array(3, 5, 7, 9),
          array(2, 4, 6, 8),
          array(1, 3, 5, 7)
          );
          >
          function add_arrays($arr ) {
          for ($row = 0; $row < count($arr[0]); $row++) {
          for ($column = 0; $column < count($arr[$column]); $column++) {
          $totals[$row] = $totals[$row] + $arr[$column][$row];
          }
          }
          print_r($totals );
          >
          }
          >
          add_arrays($arr );
          ---------------------------
          This returns the following array:
          Array ( [0] =6 [1] =12 [2] =18 [3] =24 )
          >
          These are the totals of the array's in $arr: 6 (3 + 2 + 1, added all
          first elements), 12 (5 + 4 + 3, added all second elements), etc. This
          took me quite a portion of the day to construct ;) However, I would
          like add_arrays to return a multidimensiona l array like this:
          >
          Array (
          Array ( [0] =3 [1] = 5 [2] = 7 [3] = 9 ) // 1st row
          Array ( [0] =5 [1] = 9 [2] =13 [3] =17 ) // 1st row + second
          row (i.e. 5 = 3 + 2)
          Array ( [0] =6 [1] =12 [2] =18 [3] =24 ) // 1st _ 2nd + 3rd
          row (i.e. 6 = 3 + 2 + 1)
          )
          >
          Could somebody please help me building a function that does just that?
          Adding one row to the previous one and adding the result to the output
          array? Any help would be greatly apprectiated!
          I take that back, I misread your post. Sorry.

          Example to follow anyway. :D

            Comment

            • ZeldorBlat
              #4
              Re: Adding arrays

              On May 7, 11:05 am, dennis.spreng.. .@gmail.com wrote:
              Consider the following multi-dimensional array:
              ---------------------------
              $arr = array(
              array(3, 5, 7, 9),
              array(2, 4, 6, 8),
              array(1, 3, 5, 7)
              );
              >
              function add_arrays($arr ) {
              for ($row = 0; $row < count($arr[0]); $row++) {
              for ($column = 0; $column < count($arr[$column]); $column++) {
              $totals[$row] = $totals[$row] + $arr[$column][$row];
              }
              }
              print_r($totals );
              >
              }
              >
              add_arrays($arr );
              ---------------------------
              This returns the following array:
              Array ( [0] =6 [1] =12 [2] =18 [3] =24 )
              >
              These are the totals of the array's in $arr: 6 (3 + 2 + 1, added all
              first elements), 12 (5 + 4 + 3, added all second elements), etc. This
              took me quite a portion of the day to construct ;) However, I would
              like add_arrays to return a multidimensiona l array like this:
              >
              Array (
              Array ( [0] =3 [1] = 5 [2] = 7 [3] = 9 ) // 1st row
              Array ( [0] =5 [1] = 9 [2] =13 [3] =17 ) // 1st row + second
              row (i.e. 5 = 3 + 2)
              Array ( [0] =6 [1] =12 [2] =18 [3] =24 ) // 1st _ 2nd + 3rd
              row (i.e. 6 = 3 + 2 + 1)
              )
              >
              Could somebody please help me building a function that does just that?
              Adding one row to the previous one and adding the result to the output
              array? Any help would be greatly apprectiated!
              Here's one way. Obviously there are others, also.

              function add_arrays_cumu lative($arr) {
              $out = array();

              for($i = 0; $i < count($arr); $i++) {
              if(!isset($out[$i]))
              $out[$i] = array();

              for($j = 0; $j < count($arr[$i]); $j++)
              $out[$i][$j] = $arr[$i][$j] + (isset($out[$i-1][$j]) ?
              $out[$i-1][$j] : 0);
              }

              return $out;
              }


                Comment

                • dennis.sprengers@gmail.com
                  #5
                  Re: Adding arrays

                  The length of the array's may vary, as may the number of array's. But
                  all array's will be of equal length, i.e.

                  $arr = array(
                  array(3, 5, 7, 9, 23, 53, 54, 57),
                  array(2, 4, 6, 8, 23 , 2, 43, 5),
                  array(1, 3, 5, 7, 56, 45, 8, 54),
                  array(4, 4, 5, 3, 21, 3, 23, 42),
                  array(6, 3, 2, 1, 8, 33, 12, 43)
                  );

                  is also possible but

                  $arr = array(
                  array(3, 5, 7, 9, 23, 53, 54, 57),
                  array(2, 4, 6, 8, 23 , 2),
                  );

                  will never be :-) Hope this helps!


                    Comment

                    • dennis.sprengers@gmail.com
                      #6
                      Re: Adding arrays

                      Wow, thanks! It works great. I will spend the next hour or so trying
                      to understand what code you wrote and why I still can't come up with
                      stuff solutions that :-)

                      On 7 mei, 17:32, ZeldorBlat <zeldorb...@gma il.comwrote:
                      On May 7, 11:05 am, dennis.spreng.. .@gmail.com wrote:
                      >
                      >
                      >
                      Consider the following multi-dimensional array:
                      ---------------------------
                      $arr = array(
                      array(3, 5, 7, 9),
                      array(2, 4, 6, 8),
                      array(1, 3, 5, 7)
                      );
                      >
                      function add_arrays($arr ) {
                      for ($row = 0; $row < count($arr[0]); $row++) {
                      for ($column = 0; $column < count($arr[$column]); $column++) {
                      $totals[$row] = $totals[$row] + $arr[$column][$row];
                      }
                      }
                      print_r($totals );
                      >
                      }
                      >
                      add_arrays($arr );
                      ---------------------------
                      This returns the following array:
                      Array ( [0] =6 [1] =12 [2] =18 [3] =24 )
                      >
                      These are the totals of the array's in $arr: 6 (3 + 2 + 1, added all
                      first elements), 12 (5 + 4 + 3, added all second elements), etc. This
                      took me quite a portion of the day to construct ;) However, I would
                      like add_arrays to return a multidimensiona l array like this:
                      >
                      Array (
                      Array ( [0] =3 [1] = 5 [2] = 7 [3] = 9 ) // 1st row
                      Array ( [0] =5 [1] = 9 [2] =13 [3] =17 ) // 1st row + second
                      row (i.e. 5 = 3 + 2)
                      Array ( [0] =6 [1] =12 [2] =18 [3] =24 ) // 1st _ 2nd + 3rd
                      row (i.e. 6 = 3 + 2 + 1)
                      )
                      >
                      Could somebody please help me building a function that does just that?
                      Adding one row to the previous one and adding the result to the output
                      array? Any help would be greatly apprectiated!
                      >
                      Here's one way. Obviously there are others, also.
                      >
                      function add_arrays_cumu lative($arr) {
                      $out = array();
                      >
                      for($i = 0; $i < count($arr); $i++) {
                      if(!isset($out[$i]))
                      $out[$i] = array();
                      >
                      for($j = 0; $j < count($arr[$i]); $j++)
                      $out[$i][$j] = $arr[$i][$j] + (isset($out[$i-1][$j]) ?
                      $out[$i-1][$j] : 0);
                      }
                      >
                      return $out;
                      >
                      }

                        Comment

                        • Daz
                          #7
                          Re: Adding arrays

                          On May 7, 4:40 pm, dennis.spreng.. .@gmail.com wrote:
                          Wow, thanks! It works great. I will spend the next hour or so trying
                          to understand what code you wrote and why I still can't come up with
                          stuff solutions that :-)
                          >
                          On 7 mei, 17:32, ZeldorBlat <zeldorb...@gma il.comwrote:
                          >
                          On May 7, 11:05 am, dennis.spreng.. .@gmail.com wrote:
                          >
                          Consider the following multi-dimensional array:
                          ---------------------------
                          $arr = array(
                          array(3, 5, 7, 9),
                          array(2, 4, 6, 8),
                          array(1, 3, 5, 7)
                          );
                          >
                          function add_arrays($arr ) {
                          for ($row = 0; $row < count($arr[0]); $row++) {
                          for ($column = 0; $column < count($arr[$column]); $column++) {
                          $totals[$row] = $totals[$row] + $arr[$column][$row];
                          }
                          }
                          print_r($totals );
                          >
                          }
                          >
                          add_arrays($arr );
                          ---------------------------
                          This returns the following array:
                          Array ( [0] =6 [1] =12 [2] =18 [3] =24 )
                          >
                          These are the totals of the array's in $arr: 6 (3 + 2 + 1, added all
                          first elements), 12 (5 + 4 + 3, added all second elements), etc. This
                          took me quite a portion of the day to construct ;) However, I would
                          like add_arrays to return a multidimensiona l array like this:
                          >
                          Array (
                          Array ( [0] =3 [1] = 5 [2] = 7 [3] = 9 ) // 1st row
                          Array ( [0] =5 [1] = 9 [2] =13 [3] =17 ) // 1st row + second
                          row (i.e. 5 = 3 + 2)
                          Array ( [0] =6 [1] =12 [2] =18 [3] =24 ) // 1st _ 2nd + 3rd
                          row (i.e. 6 = 3 + 2 + 1)
                          )
                          >
                          Could somebody please help me building a function that does just that?
                          Adding one row to the previous one and adding the result to the output
                          array? Any help would be greatly apprectiated!
                          >
                          Here's one way. Obviously there are others, also.
                          >
                          function add_arrays_cumu lative($arr) {
                          $out = array();
                          >
                          for($i = 0; $i < count($arr); $i++) {
                          if(!isset($out[$i]))
                          $out[$i] = array();
                          >
                          for($j = 0; $j < count($arr[$i]); $j++)
                          $out[$i][$j] = $arr[$i][$j] + (isset($out[$i-1][$j]) ?
                          $out[$i-1][$j] : 0);
                          }
                          >
                          return $out;
                          >
                          }
                          Here's my version with comments. I posted it anyway, as it would have
                          been a waste of time for me not to. I think it's identical to the
                          example above, but it's a little longer...

                          <?php

                          $arr = array(
                          array(3, 5, 7, 9),
                          array(2, 4, 6, 8),
                          array(1, 3, 5, 7)
                          );

                          function add_arrays($inp ut_array) {

                          // Cteate a new tmp_array in the global scope
                          // of the function.
                          $tmp_array;

                          // Create out array which will be returned
                          $out_array = array();

                          // Add the first row of $arr
                          $out_array[] = $input_array[0];

                          // For each array from the second array in $arr...
                          //echo "<pre>",print_r ($input_array[0]),"</pre>";
                          for ($row = 1; $row < sizeof($input_a rray); $row++) {

                          // Create a new array
                          $tmp_array = array();

                          // Now, for each key in the current $arr row...
                          for ($key_num = 0; $key_num < sizeof($input_a rray[$row]); $key_num+
                          +) {

                          // Add the values of $input_array[$row-1][$key_num] to the values
                          // of the array in $output_array before ($out_array[$row]
                          [$key_num])
                          $tmp_array[$key_num] = $input_array[$row][$key_num] +
                          $out_array[$row-1][$key_num];
                          }
                          // Append the $tmp_array to the $output_array
                          $out_array[] = $tmp_array;
                          }
                          return $out_array;

                          }

                          $result= add_arrays($arr );
                          echo 'Contents of $result: <br />';
                          echo "<pre>Array 1:<br />",print_r($res ult[0]),"</pre>";
                          echo "<pre>Array 2:<br />",print_r($res ult[1]),"</pre>";
                          echo "<pre>Array 3:<br />",print_r($res ult[2]),"</pre>";
                          ?>

                            Comment

                            • Daz
                              #8
                              Re: Adding arrays

                              On May 7, 4:40 pm, dennis.spreng.. .@gmail.com wrote:
                              Wow, thanks! It works great. I will spend the next hour or so trying
                              to understand what code you wrote and why I still can't come up with
                              stuff solutions that :-)
                              >
                              On 7 mei, 17:32, ZeldorBlat <zeldorb...@gma il.comwrote:
                              >
                              On May 7, 11:05 am, dennis.spreng.. .@gmail.com wrote:
                              >
                              Consider the following multi-dimensional array:
                              ---------------------------
                              $arr = array(
                              array(3, 5, 7, 9),
                              array(2, 4, 6, 8),
                              array(1, 3, 5, 7)
                              );
                              >
                              function add_arrays($arr ) {
                              for ($row = 0; $row < count($arr[0]); $row++) {
                              for ($column = 0; $column < count($arr[$column]); $column++) {
                              $totals[$row] = $totals[$row] + $arr[$column][$row];
                              }
                              }
                              print_r($totals );
                              >
                              }
                              >
                              add_arrays($arr );
                              ---------------------------
                              This returns the following array:
                              Array ( [0] =6 [1] =12 [2] =18 [3] =24 )
                              >
                              These are the totals of the array's in $arr: 6 (3 + 2 + 1, added all
                              first elements), 12 (5 + 4 + 3, added all second elements), etc. This
                              took me quite a portion of the day to construct ;) However, I would
                              like add_arrays to return a multidimensiona l array like this:
                              >
                              Array (
                              Array ( [0] =3 [1] = 5 [2] = 7 [3] = 9 ) // 1st row
                              Array ( [0] =5 [1] = 9 [2] =13 [3] =17 ) // 1st row + second
                              row (i.e. 5 = 3 + 2)
                              Array ( [0] =6 [1] =12 [2] =18 [3] =24 ) // 1st _ 2nd + 3rd
                              row (i.e. 6 = 3 + 2 + 1)
                              )
                              >
                              Could somebody please help me building a function that does just that?
                              Adding one row to the previous one and adding the result to the output
                              array? Any help would be greatly apprectiated!
                              >
                              Here's one way. Obviously there are others, also.
                              >
                              function add_arrays_cumu lative($arr) {
                              $out = array();
                              >
                              for($i = 0; $i < count($arr); $i++) {
                              if(!isset($out[$i]))
                              $out[$i] = array();
                              >
                              for($j = 0; $j < count($arr[$i]); $j++)
                              $out[$i][$j] = $arr[$i][$j] + (isset($out[$i-1][$j]) ?
                              $out[$i-1][$j] : 0);
                              }
                              >
                              return $out;
                              >
                              }
                              Oh, and for the record, ZeldorBlat's example is much safer. My example
                              was primarily to help you understand one of the possible methods to
                              achieve what you wanted. I didn't want you to just copy it and use it
                              as it was. Hopefully my version will have helped you understand the
                              steps taken to achieve the results you wanted. If you require a better
                              explanation of anything (in ZeldorBlat's example, or my own), please
                              don't hesitate to ask.

                                Comment

                                • dennis.sprengers@gmail.com
                                  #9
                                  Re: Adding arrays

                                  @Daz - thanks! I will really help me understand. I will get back to
                                  you if I'd have any questions :-)

                                    Comment

                                    • gosha bine
                                      #10
                                      Re: Adding arrays

                                      dennis.sprenger s@gmail.com wrote:
                                      Consider the following multi-dimensional array:
                                      ---------------------------
                                      $arr = array(
                                      array(3, 5, 7, 9),
                                      array(2, 4, 6, 8),
                                      array(1, 3, 5, 7)
                                      );
                                      >
                                      function add_arrays($arr ) {
                                      for ($row = 0; $row < count($arr[0]); $row++) {
                                      for ($column = 0; $column < count($arr[$column]); $column++) {
                                      $totals[$row] = $totals[$row] + $arr[$column][$row];
                                      }
                                      }
                                      print_r($totals );
                                      }
                                      >
                                      add_arrays($arr );
                                      ---------------------------
                                      This returns the following array:
                                      Array ( [0] =6 [1] =12 [2] =18 [3] =24 )
                                      >
                                      These are the totals of the array's in $arr: 6 (3 + 2 + 1, added all
                                      first elements), 12 (5 + 4 + 3, added all second elements), etc. This
                                      took me quite a portion of the day to construct ;) However, I would
                                      like add_arrays to return a multidimensiona l array like this:
                                      >
                                      Array (
                                      Array ( [0] =3 [1] = 5 [2] = 7 [3] = 9 ) // 1st row
                                      Array ( [0] =5 [1] = 9 [2] =13 [3] =17 ) // 1st row + second
                                      row (i.e. 5 = 3 + 2)
                                      Array ( [0] =6 [1] =12 [2] =18 [3] =24 ) // 1st _ 2nd + 3rd
                                      row (i.e. 6 = 3 + 2 + 1)
                                      )
                                      >
                                      Could somebody please help me building a function that does just that?
                                      Adding one row to the previous one and adding the result to the output
                                      array? Any help would be greatly apprectiated!
                                      >
                                      hi, how about

                                      function plus($a, $b) { return $a + $b; }

                                      $res = array(array_shi ft($arr));
                                      foreach($arr as $row)
                                      $res[] = array_map('plus ', end($res), $row);


                                      simple, huh? ;))



                                      --
                                      gosha bine

                                      extended php parser ~ http://code.google.com/p/pihipi
                                      blok ~ http://www.tagarga.com/blok

                                        Comment

                                        • Rami Elomaa
                                          #11
                                          Re: Adding arrays

                                          ZeldorBlat kirjoitti:
                                          On May 7, 11:05 am, dennis.spreng.. .@gmail.com wrote:
                                          >Consider the following multi-dimensional array:
                                          >---------------------------
                                          >$arr = array(
                                          > array(3, 5, 7, 9),
                                          > array(2, 4, 6, 8),
                                          > array(1, 3, 5, 7)
                                          >);
                                          >>
                                          >function add_arrays($arr ) {
                                          > for ($row = 0; $row < count($arr[0]); $row++) {
                                          > for ($column = 0; $column < count($arr[$column]); $column++) {
                                          > $totals[$row] = $totals[$row] + $arr[$column][$row];
                                          > }
                                          > }
                                          > print_r($totals );
                                          >>
                                          >}
                                          >>
                                          >add_arrays($ar r);
                                          >---------------------------
                                          >This returns the following array:
                                          >Array ( [0] =6 [1] =12 [2] =18 [3] =24 )
                                          >>
                                          >These are the totals of the array's in $arr: 6 (3 + 2 + 1, added all
                                          >first elements), 12 (5 + 4 + 3, added all second elements), etc. This
                                          >took me quite a portion of the day to construct ;) However, I would
                                          >like add_arrays to return a multidimensiona l array like this:
                                          >>
                                          >Array (
                                          > Array ( [0] =3 [1] = 5 [2] = 7 [3] = 9 ) // 1st row
                                          > Array ( [0] =5 [1] = 9 [2] =13 [3] =17 ) // 1st row + second
                                          >row (i.e. 5 = 3 + 2)
                                          > Array ( [0] =6 [1] =12 [2] =18 [3] =24 ) // 1st _ 2nd + 3rd
                                          >row (i.e. 6 = 3 + 2 + 1)
                                          >)
                                          >>
                                          >Could somebody please help me building a function that does just that?
                                          >Adding one row to the previous one and adding the result to the output
                                          >array? Any help would be greatly apprectiated!
                                          >
                                          Here's one way. Obviously there are others, also.
                                          >
                                          function add_arrays_cumu lative($arr) {
                                          $out = array();
                                          >
                                          for($i = 0; $i < count($arr); $i++) {
                                          This is hair-splitting, but since count($arr) is static, it would save
                                          some cpu cycles to store it in a variable instead of calling count() on
                                          each iteration:

                                          for($i = 0, $limit=count($a rr); $i < $limit ; $i++) {

                                          Or better yet, iterate the array with foreach:

                                          foreach($arr as $i =$row) {
                                          if(!isset($out[$i]))
                                          $out[$i] = array();
                                          >
                                          for($j = 0; $j < count($arr[$i]); $j++)
                                          Same goes here.

                                          I've gotten so used to foreach that I'm missing it a lot when I'm using
                                          a language that hasn't got such a structure... It's so convinient.

                                          --
                                          Rami.Elomaa@gma il.com

                                          "Wikipedia on vähän niinq internetin raamattu, kukaan ei pohjimmiltaan
                                          usko siihen ja kukaan ei tiedä mikä pitää paikkansa." -- z00ze

                                            Comment

                                            • ZeldorBlat
                                              #12
                                              Re: Adding arrays

                                              On May 7, 1:21 pm, Rami Elomaa <rami.elo...@gm ail.comwrote:
                                              ZeldorBlat kirjoitti:
                                              >
                                              >
                                              >
                                              On May 7, 11:05 am, dennis.spreng.. .@gmail.com wrote:
                                              Consider the following multi-dimensional array:
                                              ---------------------------
                                              $arr = array(
                                              array(3, 5, 7, 9),
                                              array(2, 4, 6, 8),
                                              array(1, 3, 5, 7)
                                              );
                                              >
                                              function add_arrays($arr ) {
                                              for ($row = 0; $row < count($arr[0]); $row++) {
                                              for ($column = 0; $column < count($arr[$column]); $column++) {
                                              $totals[$row] = $totals[$row] + $arr[$column][$row];
                                              }
                                              }
                                              print_r($totals );
                                              >
                                              }
                                              >
                                              add_arrays($arr );
                                              ---------------------------
                                              This returns the following array:
                                              Array ( [0] =6 [1] =12 [2] =18 [3] =24 )
                                              >
                                              These are the totals of the array's in $arr: 6 (3 + 2 + 1, added all
                                              first elements), 12 (5 + 4 + 3, added all second elements), etc. This
                                              took me quite a portion of the day to construct ;) However, I would
                                              like add_arrays to return a multidimensiona l array like this:
                                              >
                                              Array (
                                              Array ( [0] =3 [1] = 5 [2] = 7 [3] = 9 ) // 1st row
                                              Array ( [0] =5 [1] = 9 [2] =13 [3] =17 ) // 1st row + second
                                              row (i.e. 5 = 3 + 2)
                                              Array ( [0] =6 [1] =12 [2] =18 [3] =24 ) // 1st _ 2nd + 3rd
                                              row (i.e. 6 = 3 + 2 + 1)
                                              )
                                              >
                                              Could somebody please help me building a function that does just that?
                                              Adding one row to the previous one and adding the result to the output
                                              array? Any help would be greatly apprectiated!
                                              >
                                              Here's one way. Obviously there are others, also.
                                              >
                                              function add_arrays_cumu lative($arr) {
                                              $out = array();
                                              >
                                              for($i = 0; $i < count($arr); $i++) {
                                              >
                                              This is hair-splitting, but since count($arr) is static, it would save
                                              some cpu cycles to store it in a variable instead of calling count() on
                                              each iteration:
                                              >
                                              for($i = 0, $limit=count($a rr); $i < $limit ; $i++) {
                                              >
                                              Or better yet, iterate the array with foreach:
                                              >
                                              foreach($arr as $i =$row) {
                                              >
                                              if(!isset($out[$i]))
                                              $out[$i] = array();
                                              >
                                              for($j = 0; $j < count($arr[$i]); $j++)
                                              >
                                              Same goes here.
                                              >
                                              I've gotten so used to foreach that I'm missing it a lot when I'm using
                                              a language that hasn't got such a structure... It's so convinient.
                                              >
                                              --
                                              Rami.Elo...@gma il.com
                                              >
                                              "Wikipedia on vähän niinq internetin raamattu, kukaan ei pohjimmiltaan
                                              usko siihen ja kukaan ei tiedä mikä pitää paikkansa." -- z00ze
                                              Yes -- you're correct on both. In the normal course of things I would
                                              save the value of count() and also use a foreach instead. Using
                                              count() over and over again makes it a bit easier to follow the code,
                                              and the OP was using regular for loops so I stuck with those.

                                              In practice I use foreach almost exclusively -- and you're right in
                                              that I really miss it in other languages :)

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