php - update foreach variable inner it

Question

I have an array:

$colors = array("red", "green");

I am using this array in foreach and I want to update this array inner the foreach for example like this:

foreach( $colors as $color ){
    if( $color=='green' ){
        array_push($colors, 'blue');  //now $colors is ["red", "green", "blue"]
    }
    echo $color . "<br>";
}

Result is:

red
green

and blue is not echo in result!

How I can update foreach variable inner it?

update: I do this with for and it is work.

$colors = array("red", "green");

for( $i=0; $i < count($colors); $i++ ){
    if( $colors[$i]=='green' ){
        array_push($colors, 'blue'); //now $colors is ["red", "green", "blue"]
    }
    echo $colors[$i]."<br>";
}

result is

red
green
blue

How I can do this with foreach?

stackoverflow.com/questions/10057671/… may be worth a read to see how foreach works. — Nigel Ren
– Nigel Ren, Commented May 8, 2020 at 13:55

Felippe Duarte · Accepted Answer · 2020-05-08 14:01:04Z

3

If you pass as reference (https://www.php.net/manual/en/language.references.php) (see &$color) it will work as it will point to the same memory address, thus updating the $colors var:

<?php
$colors = array("red", "green");
foreach( $colors as &$color ){
    if( $color=='green' ){
        array_push($colors, 'blue');
    }
    echo $color . "<br>";
}

Of course there is no need for this if you print $colors outside the loop, with print_r($colors);. This pass by reference is only needed inside the loop.

edited May 8, 2020 at 14:01

answered May 8, 2020 at 13:58

Felippe Duarte

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1 Comment

AbraCadaver Over a year ago

I had forgotten that it behaved that way with the reference.

Feroz · Accepted Answer · 2020-05-08 14:26:06Z

-1

foreach($colors as $color){
   if( $color=='green' ){
      $colors[]= 'blue';  //now $colors is ["red", "green", "blue"]
   }
}

Now use foreach loop to print all values under $color variable

foreach($colors as $color){
   echo $color."\n";
}

answered May 8, 2020 at 14:26

Feroz

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