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How to Add Element to end of currently Iterating array


sen5241b
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 <!DOCTYPE html>
<html>
<body>

<?php  
$colors = array("red", "green", "blue", "yellow"); 

foreach($colors as $x => $value):
  echo "$value <br>";
  if ($x == 1) $colors[] = "pink";
endforeach;
?>  

</body>
</html>

Getting error 

PHP Parse error: syntax error, unexpected '$colors' (T_VARIABLE) in /home/KhtmoB/prog.php on line 10

Edited by sen5241b
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  • sen5241b changed the title to How to Add Element to end of currently Iterating array

When you use foreach() you iterate through a copy of the array elements but you are adding 'pink' to the original array.

To iterate through the original array you need to pass the values "by reference". For example

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

foreach($colors as $x => &$value):                // note the "&"
  echo "$value <br>";
  if ($x == 1) $colors[] = "pink";
endforeach;

giving

red 
green 
blue 
yellow 
pink 

 

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You can also use an ArrayIterator and the append method.

From a random project I was working on,

$u = new \ArrayIterator([1], \ArrayIterator::STD_PROP_LIST);
while($u->valid()){
    $x = 2 * $u->current() + 1;
    $y = 3 * $u->current() + 1;
    if($u->key() == $n){ // this is set elsewhere in the method; not really important for this example
        break;
    }
    $u->append($x);
    $u->append($y);
    $u->asort();
    $u->next();
}

 

Edited by maxxd
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For makes copy of array and works off of the copy. Appended elements are added to array but not to the time copy. You cannot process the appended elements in the initial for loop.

 


<!DOCTYPE html>
<html>
<body>

<?php
$ptr = 0;
$colors = array("red", "green", "blue", "yellow"); 
$colors[] = 'pink';
foreach ($colors as $key => $value) {
  echo "$key <br>";
  echo "$value <br>";
  if ($key == 1) 
  { $colors[] = 'purple';
  }
}
echo '<br>';
print_r($colors);
?>  
    
</body>
</html>

 

Edited by sen5241b
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