PHP array question

Question

This is more of a conceptual question concerning the built in functionality of PHP and arrays. I was wondering if there is any way to do the following:

You have an array $a and this array contains 5 elements (0-4) for the purpose of this example.

Is there any way to make a new array, which would contain the following:

  $b[0] = $a[0];
  $b[1] = $a[0] + $a[1];
  $b[2] = $a[0] + $a[1] + $a[2];
  $b[3] = $a[0] + $a[1] + $a[2] + $a[3]; 
  $b[4] = $a[0] + $a[1] + $a[2] + $a[3] + $a[4];
  etc..

I imagine an example of it's use would be bread crumbs on a website, where you could click on any directory of a given link like /dir1/dir2/dir3/dir4

Is there anything built into PHP that can handle building up an array in this fashion? Or examples of a function which handles this? Or even a better way to go about this.

Thanks!

EDIT: Here is the final solution via the help of you guys! This will build the link, and create the proper link for each directory/element.

//$a is our array


$max = count($a);
foreach (range(1,$max) as $count) {
   $b[] = implode("/", array_slice($a, 0, $count));
}
foreach($b as $c) {
   $x = explode('/' , $c);
   $y = array_pop($x);
   echo "<a href='$c'>".$y."</a>"."/"; 
}

score 4 · Accepted Answer · answered Jun 06 '11 at 01:19

4

If you just want the five combinations as in your example then:

foreach (range(1,5) as $count) {
    $b[] = implode("/", array_slice($a, 0, $count));
}

answered Jun 06 '11 at 01:19

mario

144,265
20
237
291

This worked perfectly. I just replaced `5` with the count of the array in question, and now it works dynamically. – Richard Easton Jun 06 '11 at 01:25
@Richard: Cool if it helped! - Btw, you now have enough reputation to also upvote answers. So take your time to upvote the other answers here too (shows appreciation regardless of if it worked and guarantees that you get as many people answering for all your next questions). – mario Jun 06 '11 at 01:28
Thanks Mario, got me an upvote! Right back atcha. Good solution too. – Ben Jun 06 '11 at 01:29
Unfortunately I do not have an account and cannot, but I will definitely make one now as I am pretty sure all of these other ones work as well. – Richard Easton Jun 06 '11 at 01:31

score 1 · Answer 2 · answered Jun 06 '11 at 01:17

You'd be best with a recursive function in that case.

$arr = array('dir1', 'dir2', 'dir3', 'dir4', 'dir5');

function breadcrumbs($a)
{
  // Remove first value
  $first = array_shift($a);

  // Loop through other values
  foreach ($a as $key => $value)
  {
    // Add first to remaining values
    $a[$key] = $first . '/' . $value;
  }

  // Return array
  return array($first) + breadcrumbs($a);
}

Untested, but should work. It will make each sequential value contain the values before it in the array.

score 1 · Answer 3 · answered Jun 06 '11 at 01:20

1

$b = array();

for($i=0;$i<count($a);$i++) { 
  $b[] = array_sum(array_splice($a,0,$i)); 
}

answered Jun 06 '11 at 01:20

Ben

54,723
49
178
224

score 0 · Answer 4 · answered Jun 06 '11 at 01:20

0

I think, you want something like this:

for($i = 0; $i < count($a); $i++)  
  for($j = 0; $j < i + 1; $j++)
     $b[i] += $a[j];

answered Jun 06 '11 at 01:20

Racooon

1,468
2
10
28

2

+ is a numeric operator, not a string operator in PHP. This won't work. It would have to be .=, and even that wouldn't work for what he asked. – RétroX Jun 06 '11 at 01:41

PHP array question

4 Answers4