Re: [PHP] Rewind foreach loop

At 2:11 PM +1100 11/30/07, Jeffery Fernandez wrote:
On Fri, 30 Nov 2007 02:01:47 pm Chris <dmagick@xxxxxxxxx> wrote:
Jeffery Fernandez wrote:
> Hi all,
>
> Is it possible to rewind a foreach loop? eg:
>
>
> $numbers = array(0,1,2,3,4,5,6,7,8,9,10);
>
> foreach ($numbers as $index => $value)
> {
> if ($value == 5)
> {
> prev($numbers);
> }
> > echo "Value: $value" . PHP_EOL;
> }
>
> The above doesn't seem to work. In one of my scenarios, when I encounter
> and error in a foreach loop, I need the ability to rewind the array
> pointer by one. How can I achieve this?

echo $numbers[$index-1] . PHP_EOL;

That will only give me the value of the previous index. What I want is to
rewind the array pointer and continue with the loop.


I would think that if you rewound the array pointer as above, you'd simply end up in an infinite loop, as you'd keep hitting the condition that triggered the rewind. So I'm assuming you have some other test in there and this is just a stripped down example.

If you're using a one-dimensional array, as opposed to a multidimensional and/or associative array, you can do (untested):

$Count = count($numbers);

for ($i=0; $i<$Count; $i++) {
$value = $numbers[$i];
if ($value == 5 && some_other_test()) {
$value = $numbers[--$i];
}
echo "Value: $value" . PHP_EOL;
}

Wouldn't be much more complex to extend to a multidimensional array with an integer index. If you were using an associative array with a string index, you'd probably have to do something like

$NotJustNumbers = array('a'=>'slurm', 'b'=>'fry', 'c'=>'leela');
$Keys = array_keys($NotJustNumbers);
$Count = count($Keys);

for ($i=0; $i<$Count; $i++) {
$value = $NotJustNumbers[$Keys[$i]];
if ($value == 5 && some_other_test()) {
$value = $NotJustNumbers[$Keys[--$i]];
}
echo "Value: $value" . PHP_EOL;
}


- steve

--
+--------------- my people are the people of the dessert, ---------------+
| Steve Edberg http://pgfsun.ucdavis.edu/ |
| UC Davis Genome Center sbedberg@xxxxxxxxxxx |
| Bioinformatics programming/database/sysadmin (530)754-9127 |
+---------------- said t e lawrence, picking up his fork ----------------+
.

Relevant Pages

  • Re: [PHP] Rewind foreach loop
    ... Is it possible to rewind a foreach loop? ... you can't rewind the array. ... Also you want to reset() the array before looping ...
    (php.general)
  • Re: Locating an element within an array
    ... the array and check for certain values. ... SLP and return the last 3 integers. ... With the foreach loop this becomes: ... The problem with this line is you are using a numeric comparison ...
    (perl.beginners)
  • Re: [PHP] Rewind foreach loop
    ... 30 Nov 2007 02:01:47 pm Chris wrote: ... Is it possible to rewind a foreach loop? ... rewind the array pointer and continue with the loop. ...
    (php.general)
  • Re: foreach statement output
    ... by using a 'for' statement instead of the foreach loop: ... I thought you wanted a string. ... Why are you declaring an array instead? ... Eliminate duplicate strings completely? ...
    (comp.infosystems.www.authoring.cgi)
  • Re: Input error checking on arrays..
    ... >> It would be ideal if instead of even going with a foreach loop, ... > to check every member of the array for certain characteristics, ... > And you can't check every member of an array without looping through the ... input error output file I've got (in which I indicate what the error ...
    (comp.lang.php)