Reset/remove all values in an array in PHP

I have an array_flipped array that looks something like:

{ "a" => 0, "b" => 1, "c" => 2 }

Is there a standard function that I can use so it looks like (where all the values are set to 0?):

{ "a" => 0, "b" => 0, "c" => 0 }

I tried using a foreach loop, but if I remember correctly from other programming languages, you shouldn't be开发者_运维知识库 able to change the value of an array via a foreach loop.

foreach( $poll_options as $k => $v )
  $v = 0; // doesn't seem to work...

tl; dr: how can I set all the values of an array to 0? Is there a standard function to do this?

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$array = array_fill_keys(array_keys($array), 0);

or

array_walk($array, create_function('&$a', '$a = 0;'));

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You can use a foreach to reset the values;

foreach($poll_options as $k => $v) {
  $poll_options[$k] = 0;
}

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array_fill_keys function is easiest one for me to clear the array. Just use like

array_fill_keys(array_keys($array), "")

or

array_fill_keys(array_keys($array), whatever you want to do)

foreach may cause to decrease your performance to be sure that which one is your actual need.

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Run your loop like this, it will work:

foreach( $poll_options as $k => $v )
    $poll_options[$k] = 0;

Moreover, ideally you should not be able to change the structure of the array while using foreach, but changing the values does no harm.

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As of PHP 5.3 you can use lambda functions, so here's a functional solution:

$array = array_map(function($v){ return 0; }, $array);

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You have to use an ampersand...

foreach( $poll_options as &$v)
  $v = 0;

Or just use a for loop.

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you can try this

foreach( $poll_options as $k => &$v )
    $v = 0; 

Address of $v

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array_combine(array_keys($array), array_fill(0, count($array), 0))

Would be the least manual way of doing it.

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There are two types for variable assignment in PHP,

1. Copy
2. Reference

In reference assignment, ( $a = &$b ), $a and $b both, refers to the same content. ( read manual )

So, if you want to change the array in thesame time as you doing foreach on it, there are two ways :

1- Making a copy of array :

foreach($array as $key=>$value){
        $array[$key] = 0 ; // reassign the array's value
}

2 - By reference:

foreach($array as $key => &$value){
        $value = 0 ;
}