php

change initial array inside the foreach loop?

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i want to have a foreach loop where the initial array is changed inside the loop.

eg.

$array = array('red', 'blue');
foreach($array as $key => $value) {
    $array[] = 'white';
    echo $value . '<br />';
}

in this loop the loop will print out red and blue although i add another element inside the loop.

is there any way to change the initial array inside the loop so new elements will be added and the foreach will use the new array whatever is changed?

i need this kind of logic for a specific task:

i will have a if statement that search for a link. if that link exists, it is added to the array. the link content will be fetched to be examined if it contains another link. if so, this link is added, and the content will be fetched, so on so forth.. when no link is further founded, the foreach loop will exit

Answers

I don't think this is possible with a foreach loop, at least the way you wrote it : doesn't seem to just be the way foreach works ; quoting the manual page of foreach :

Note: Unless the array is referenced, foreach operates on a copy of the specified array and not the array itself.

Edit : after thinking a bit about that note, it is actually possible, and here's the solution :

The note says "Unless the array is referenced" ; which means this portion of code should work :

$i = 0;
$array = array('red', 'blue');
foreach($array as $key => & $value) {
    $array[] = 'white';
    echo $value . '<br />';
    if ($i++ >= 5) {
        break;   // security measure to ensure non-endless loop
    }
}

Note the & before $value.

And it actually displays :

red
blue
white
white
white
white

Which means adding that & is actually the solution you were looking for, to modify the array from inside the foreach loop ;-)

Edit : and here is the solution I proposed before thinking about that note :

You could do that using a while loop, doing a bit more work "by hand" ; for instance :

$i = 0;

$array = array('red', 'blue');

$value = reset($array);
while ($value) {
    $array[] = 'white';
    echo $value . '<br />';
    if ($i++ >= 5) {
        break;   // security measure to ensure non-endless loop
    }
    $value = next($array);
}

Will get you this output :

red
blue
white
white
white
white

Thursday, September 22, 2022

asliyanage

Here's what worked best for me when trying to script this (in case anyone else comes across this like I did):

$ pecl -d php_suffix=5.6 install <package>
$ pecl uninstall -r <package>

$ pecl -d php_suffix=7.0 install <package>
$ pecl uninstall -r <package>

$ pecl -d php_suffix=7.1 install <package>
$ pecl uninstall -r <package>

The -d php_suffix=<version> piece allows you to set config values at run time vs pre-setting them with pecl config-set. The uninstall -r bit does not actually uninstall it (from the docs):

vagrant@homestead:~$ pecl help uninstall
pecl uninstall [options] [channel/]<package> ...
Uninstalls one or more PEAR packages.  More than one package may be
specified at once.  Prefix with channel name to uninstall from a
channel not in your default channel (pecl.php.net)

Options:
  ...
  -r, --register-only
        do not remove files, only register the packages as not installed
  ...

The uninstall line is necessary otherwise installing it will remove any previously installed version, even if it was for a different PHP version (ex: Installing an extension for PHP 7.0 would remove the 5.6 version if the package was still registered as installed).

Monday, December 12, 2022

shankar_damodaran

Foreach will not loop through new values added to the array while inside the loop.

If you want to add the new value between two existing values, you could use a second array:

$values = array(
    'foo' => 10,
    'bar' => 20,
    'baz' => 30
);
$newValues = array();
foreach($values as $key => $value) 
{
    $newValues[$key] = $value;
    if($key == 'bar') 
    {
        $newValues['qux'] = 21;
    }
}
print implode(' ', $newValue);

Also, see one of my favorite questions on discussing the foreach loop: How does PHP 'foreach' actually work?

Sunday, August 21, 2022

moritz_petersen

unset it first in case it is already in the proper format, otherwise you will remove what you just defined:

foreach($array as $key => $value)
    {
        unset($array[$key]);
        $array[ucfirst($key)] = $value;
    }

Thursday, August 11, 2022

kchetan

Never used any of those, but they look interesting..

Take a look at Gearman as well.. more overhead in systems like these but you get other cool stuff :) Guess it depends on your needs ..

Friday, November 11, 2022

the_falvert

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