PHP Unset Command in If Statement Not Working - php

Question

I would like to unset an HTTP Posted key from the array after it echoes the "1" result, but the unset doesn't seem to work. How can I fix this?
$keylist = array('HHH', 'GGG');
if (in_array($_POST["keys"], $keylist)){
echo "1";
unset($keylist[$_POST["keys"]]);
} else {
echo "0" ;
}
Appreciate any help,
Hobbyist

Answer 1

Your unsetting $keylist not $_POST
unset($_POST["keys"]);

Answer 2

You're using the wrong array key for unsetting (You're trying to unset $keylist["HHH"], not, say, $keylist[0]) - you'll need to retrieve the key from the array, and then unset that specifically in order to remove it from the keylist.
$index = array_search($_POST["keys"], $keylist);
if($index!==false) { //YES, NOT DOUBLE EQUALS
unset($keylist[$index));
}
If $_POST["keys"] is an array of keys, you'll need to use array_keys with a search_value instead.
Array_search documentation: http://php.net/manual/en/function.array-search.php
Array_keys documentation: http://php.net/manual/en/function.array-keys.php
EDIT: Adding a full, working example.
<?
$_POST["keys"]="asdjkgldshglsjhgsdlhgsdlghsdlghsdlgh";
$keylist=array("asdjkgldshglsjhgsdlhgsdlghsdlghsdlgh","derp2");
if(in_array($_POST["keys"], $keylist)) {
$indexToRemove = array_search($_POST["keys"], $keylist);
echo "1";
print_r($keylist);
unset($keylist[$indexToRemove]);
print_r($keylist);
} else {
echo "0";
print_r($keylist);
}
?>
Another example, this time checking the index itself to see if it is not false:
<?
$_POST["keys"]="asdjkgldshglsjhgsdlhgsdlghsdlghsdlgh";
$keylist=array("asdjkgldshglsjhgsdlhgsdlghsdlghsdlgh","derp2");
$indexToRemove = array_search($_POST["keys"], $keylist);
if($indexToRemove!==false) {
echo "1";
print_r($keylist);
unset($keylist[$indexToRemove]);
print_r($keylist);
} else {
echo "0";
print_r($keylist);
}
?>
Output:
1Array ( [0] => asdjkgldshglsjhgsdlhgsdlghsdlghsdlgh [1] => derp2 ) Array ( [1] => derp2 )
I realize now that I only had one = on the $index!==false check - the reason you need two is because $index is 0 if you're removing the first element of an array. Per PHP documentation,
Warning
This function may return Boolean FALSE, but may also return a non-Boolean
value which evaluates to FALSE. Please read the section on Booleans for more
information. Use the === operator for testing the return value of this function.

Answer 3

in_array($_POST["keys"], $keylist) checks if the posted value $_POST["keys"] is present as a value in $keylist, but unset($keylist[$_POST["keys"]]) uses $_POST["keys"] as the key in $keylist to unset something.
Since in_array() returns true, the posted value is present in the array $keylist. But you can't do unset($keylist['GGG']) because that value is not set.
A simple solution is to use the same values as keys too:
$keylist = array('HHH', 'GGG');
$keylist = array_combine($keylist, $keylist);
More about array_combine().

Answer 4

Your array have keys. So "HHH" in keylist is $keylist[0] and not $keylist['HHH']. You can not unset it because you have to define the array key instead of the array value.
Try to search for the array value like this:
array_search($_POST["keys"], $keylist)
This will return the array key for you or false if its not found. Your full code should like look like:
echo "1";
$arrkey = array_search($_POST["keys"], $keylist);
if( $arrkey !== false ){
unset($keylist[$arrkey]);
}
Here the PHP Manual for the array_search function: http://php.net/manual/en/function.array-search.php