PHP: unset from array using if statement

There are many ways to Rome, as they say..

Using foreach()

A cleaner approach would be to use foreach instead of for loops, and checking against an array using in_array() instead of individually checking all the fruits.

$fruits = ['apple', 'orange', 'melon', 'banana', 'pineapple'];

foreach ($fruits as $key=>$fruit) {
    if (in_array($fruit, ['apple', 'orange', 'melon', 'banana'])) {
        unset($fruits[$key]);
    }
}
print_r($fruits);

Using array_filter()

A more "fancy" way would be a one-liner using array_filter(),

$fruits = ['apple', 'orange', 'melon', 'banana', 'pineapple'];

$fruits = array_filter($fruits, function($fruit) {
    return !in_array($fruit, ['apple', 'orange', 'melon', 'banana']);
});
print_r($fruits);

Using array_diff()

Even simpler, use array_diff(), which finds all elements that exists in only one of the arrays (essentially removing the duplicates).

$fruits = ['apple', 'orange', 'melon', 'banana', 'pineapple'];
$remove = ['apple', 'orange', 'melon', 'banana'];
$result = array_diff($fruits, $remove);

Using array_intersect()

There's also array_intersect, which is sort of the inverse of array_diff(). This would find elements that exists in both arrays, and return that.

$fruits = ['apple', 'orange', 'melon', 'banana', 'pineapple'];
$find = ['pineapple'];
$result = array_intersect($fruits, $find); 

• Live demo using foreach()
• Live demo using array_filter()
• Live demo using array_diff()
• Live demo using array_intersect()
• PHP.net on in_array()
• PHP.net on array_diff()
• PHP.net on array_filter()
• PHP.net on array_intersect()
• PHP.net on foreach()

Because after removing the first 3 element the $i value is 3 but the count of the array is 2 so the for loop breaks - remember the loop condition is re-evaluating in each iteration. Change to this will give you the desire output:

$size = count($fruits)
for ($i = 0 ; $i < $size; $i++){ 

Generally, using unset with for loop with int index is not recommended

I think problem is $i<count($fruits). It reduce the array size. So it's runs only 3 times. SO assign the array size to variable first.

<?php 

    $fruits = ['apple', 'orange', 'melon', 'banana', 'pineapple'];
    $n=count($fruits);
    for ($i = 0 ; $i <$n ; $i++){ 

     if ($fruits[$i] == 'apple' || $fruits[$i] == 'orange' || $fruits[$i] == 'melon' || $fruits[$i] == 'banana'){
         unset($fruits[$i]);
      }
     }
     print_r($fruits);

?>