Deleting key & value element of array by using unset command in PHP

$input=array(a,b,c,d,e,f,g);
// Remove 4th element ( 0 indexed ) 
unset($input[3]); 
while (list ($key, $val) = each ($input)) {
echo "$key -> $val <br>";
}

As we are deleting the third element (4th on 0 index) the output of above code is here.

0 -> a 
1 -> b 
2 -> c 
4 -> e 
5 -> f 
6 -> g

We can remove an element from an array by using unset command.
This unset command takes the array key as input and remove that element from the array. After removal the associated keys and values ( of other balance elements ) does not change.

Remove any element of PHP array by using unset, array_diff() or by searching for value & using key

unset($input[3]);

Here we are removing the element with key=3. If the array has 7 elements and if try to delete 9th element then unset command will not return any error but nothing will be deleted.

Here is an example how unset command is used.

How to delete an element by using value ( not key ) from an array

In the above examples we have used key if the array as input to remove the element from the array. If we don't know the key and we know the value then how to remove the element?

There is no direct function to do this but we can use array_diff function to remove the element by using the value. Note that array_diff function takes two arrays as input. Here is the code , we want to remove d from our $input array.

$new_array=array_diff($input,array("d"));

We can also use like this to remove more elements by using its value.

$remove=array(c,f);
$new_array=array_diff($input,$remove);

Display & check our elements after removal like this.

while (list ($key, $val) = each ($new_array)) {
echo "$key -> $val <br>";}

The output of the above command is here

0 -> a 
1 -> b 
3 -> d
4 -> e 
6 -> g

You can read how unset a variable here.

Using array_search()

We can use array_search() to get the key of matching search and then delete by using unset()

$input=array(a,b,c,d,e,f,g);

unset($input[array_search('d',$input)]);

while (list ($key, $val) = each ($input)) {
echo "$key -> $val <br>";
}

Output is here

0 -> a
1 -> b
2 -> c
4 -> e
5 -> f
6 -> g

Example 2: Unsetting Multiple Elements Conditionally

Sometimes, you may want to remove elements from an array based on a condition:

$arr = array(10, 20, 30, 40, 50);
foreach ($arr as $key => $value) {
    if ($value % 20 == 0) {
        unset($arr[$key]);
    }
}
print_r($arr); // Output: Array ( [0] => 10 [2] => 30 [4] => 50 )

Example 3: Unsetting the Entire Array

You can completely remove the array using *unset()*:

$arr = array(1, 2, 3);
unset($arr);
echo isset($arr) ? "Array exists" : "Array is unset"; // Output: Array is unset

Example 4: Unsetting a Key in an Associative Array

$arr = array("name" => "John", "age" => 30, "city" => "NY");
unset($arr['age']);
print_r($arr); // Output: Array ( [name] => John [city] => NY )

Array Adding & Removing Elements
array_pop(): Removing Last element of the Array
array_shift(): Removing First element of the Array
array_unset(): Removing element from any position of the Array
array_push(): Adding elements at the end of the Array
array_unshift(): Adding elements at the beginning of the Array

Questions

How do you delete a specific key-value element from an array using the `unset` command in PHP?
What is the syntax for using the `unset` command to remove an element from an array?
Can you delete multiple key-value elements from an array using a single `unset` command in PHP?
How do you handle cases where the specified key does not exist in the array while using `unset`?
Can you use the `unset` command to delete nested or multidimensional array elements in PHP?
What are the effects of using `unset` on an array? Does it reindex the remaining elements?
How do you check if an element has been successfully deleted from an array after using `unset`?
Are there any alternative methods or functions in PHP to delete elements from an array, other than `unset`?
What precautions should be taken when using `unset` to delete elements from an array to avoid unexpected behavior?
Can you use the `unset` command to remove an element by its value rather than its key in PHP?

Joining Two Arrays by array_merge
Array REFERENCE

Subhendu Mohapatra

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PHP deleting elements of an array by unset ( key or value )