Selecting 1st -> nth element in an array

[Rodders]

My code contains a loop which is handling single lines from a text file. It splits each line into an array.

I know what the first element is, and I know what the last three elements are. Those are also easy to pull out of the array by using $array[0], end($array) and prev($array).

Where I'm having problems is getting everything in between. It could be that between the 1st element and the last 4 that I have anything between 1 and 7 elements.

I need a way of getting all of those elements into one variable with spaces in between.

Any suggestions ?

I'm sure there's several methods, but I can't think of one that doesn't involve 800 lines of code !

[eoghain]

$array = array("this", "is", "my", "string");
$arrayAsString = implode(" ", $array);
print $arrayAsString;

There you go, an array turned into a space separated string in a single line of code (3 if you are picky and want to include my example code).

[Rodders]

but it's not quite what I'm after

my array can vary in length / no of elements. I need to be able to select the 2nd element then each next element until I am 4 from the end.

$array1 = array("this", "is", "an", "extra", "long", "example", "for", "my", "string"); 
// I need to create a variable that contains just "is an extra long example"


$array2 = array("this", "is", "a", "really", "massive", "silly", "way", "to", "show", "an", "example", "of", "an", "extra", "long", "example", "for", "my", "string");

// I need to create a variable that contains just "is a really massive silly way to show an example of an extra long example"

Can you see how the variable always starts with the 2nd elements and always ends at the elements 4th from the end, regardless of the number of elements ?

[eoghain]

Sorry I miss understood what you want, but that is just as easy.

function stringifyArray($array)
{
   $output = "";  // return variable
   $sep = ""; // separator, set after the first element

   for ($i = 1; $i < (count($array) - 2); $i++)
   {
      $output .= $sep . $array[$i];
      $sep = " ";  // set separator to be a space
   }

   return $output;
}


$array1 = array("this", "is", "an", "extra", "long", "example", "for", "my", "string");  

print stringifyArray($array1);

$array2 = array("this", "is", "a", "really", "massive", "silly", "way", "to", "show", "an", "example", "of", "an", "extra", "long", "example", "for", "my", "string");

print stringifyArray($array2);

[Rodders]

that's an awesomely simple piece of code, and I'm sure it'll work just great. I've just found a function called array_slice() which may do something similar, but for the moment I'm happy.

Thanks

[eoghain]

Yep, you could use [man]array_slice/man with [man]implode/man to do the same thing I've done with my function. I tend to write things out long hand before finding functions that would make things easier.

Here is my example using these functions:

$array1 = array("this", "is", "an", "extra", "long", "example", "for", "my", "string");

print implode(" ", array_slice($array1, 1, (count($array1) - 3));

Need to subtract 3 from the length of the array because we don't want the 1st element or the last 2.

[Rodders]

That's far more elegant......I need to do some reading on arrays because I tried this without the implode() and it didn't work.

I just don't understand implode() or explode() or arrays properly.

[eoghain]

Well implode is easy, look at the function I wrote earlier, it is basically implode.

Here is how I would write both implode and explode in PHP:

// Personal implode function
// Does exactly what implode does.
function my_implode($separator, $array)
{
   $output = "";
   $sep = "";

   foreach ($array as $item)
   {
      $output = $sep . $item;
      $sep = $separator;
   }

   return $output;
}

// Personal explode function
// Does exaclty what explode does
function my_explode($separator, $string)
{
   $output = array();
   $startchar = 0;

   for ($i = 0; $i < strlen($string); $i++)
   {
      if (substr($i, 1) == $separator)
      {
         $output[] = substr($startchar, ($i - $startchar));
         $startchar = ++$i;
      }
   }

   return $output;
}

See fairly simple. I'm sure there are better ways of doing this that are faster and more optomized, but they aren't that difficult to write.

Arrays sometimes take awhile to get your head around, but once you do they are very simple things.