Removing array elements based on a different array

[jwhite68]

I'll illustrate my issue with a simpler example.

 

Suppose I have an array called countries with entries:

 

$countries["us"] = "United States";
$countries["ca"] = "Canada";
$countries["al"] = "Albania";
$countries["dz"] = "Algeria";

 

Now, lets suppose I have another array, country2, which has the following:

 

$countries2["ca"] = "Canada";
$countries2["al"] = "Albania";

 

I effectivelty want a way to remove the array elements that are in country2, from the country array. and produce a new resultant array $country_list.

So after processing, what I am left with is the following (for this example):

 

$country_list["us"] = "United States";
$country_list["dz"] = "Algeria";

 

Does anyone have any advice, sample code that could achieve this?

In the actual code, country2 will change dynamically - ie the countries that need removing will change each time the form loads (or may change).

[trq]

<?php

  $country_list = array_diff($countries,$country2);

?>

[jwhite68]

Thanks, but I just realised something.

 

My country2 array is actually not in the same format.  Its like this:

 

[0] => ai [1] => au [2] => ca [3] => us

 

So its values contain the 'keys' for the index of the other array, namely - $countries.  How would I get the same result, with this situation?

[jwhite68]

[code]I am trying to achieve the result with the following code:

foreach ($countries as $key2 => $value2) {

$dont_output=0;

foreach ($country2 as $key3 => $value3) if (array_key_exists('"'.$value3.'"',$countries)) dont_output=1;

if ($dont_output==0) echo '<option value="'.$key2.'">'.$countries["$key2"].'</option>';

}

[/code]

 

What I am actually trying to do, is build a drop down list of 'option values', from $countries, but ensuring that any entries that are in $country2 do not appear in the output. Since the values of the array elements in $country2 are the key/index values for $country, I thought I would be able to use the array_key_exists function to compare a value of $country2, against the index values in $countries.

 

However, at runtime, this always outputs the whole contents of $countries still, via the option value statements.  ie. $dont_output is never set to 1.

[jwhite68]

I was able to resolve by changing:

 

if (array_key_exists('"'.$value3.'"',$countries)) dont_output=1;

 

to

 

if ($value3==$key2) $dont_output=1;

 

It now works.  Although I am sure there must be a quicker and neater way in PHP...

[per1os]

<?php
foreach ($countries as $key => $value) { 
    if (!in_array($key, $country2)) {
       echo '<option value="'.$key.'">'.$value].'</option>';
    } 
}
?>

 

Your logic was all FUBAR'ed up.

 

EDIT: Updated the function to do it correctly.