Website construction - how PHP deletes duplicate elements in an array

This article describes how PHP deletes duplicate elements in an array through the array_unique() function. If you need help, you can learn

Array_unique() function

Array_unique() function sorts the values of array elements as strings, and then only retains the first key name for each value, ignoring all subsequent key names, which is to delete the duplicate elements in the array.

Code example:

 $result1 = array("a" => "green", "red", "b" => "green", "blue", "red");

 var_dump($result1);

 $result2 = array_unique($result1);

 var_dump($result2);

 ?>

Output:

Array (size=5)

‘a’=>string ’green’ (length=5)

   0 => string ‘red’ (length=3)

‘b’ => string ‘green’ (length=5)

   1 => string ‘blue’ (length=4)

   2 => string ‘red’ (length=3)

Array (size=3)

‘a’=>string ’green’ (length=5)

   0 => string ‘red’ (length=3)

   1 => string ‘blue’ (length=4)

Array_flip() function

Array ­_ The flip () function is used to reverse/exchange all the key names in the array and their associated key values.

The array_flip() function returns an inverted array. If the same value occurs multiple times, the last key name will be its value, and all other key names will be lost. Using this feature, we can indirectly realize array de duplication.

Code example:

 header("content-type:text/html;charset=utf-8");

$a = array(1, 5, 2, 5, 1, 3, 2, 4, 5);

//Output original array

Echo "Original array:";

var_dump($a);

//Remove duplicate values by using flip keys and values

$a = array_flip($a);

//Restore array elements by flipping keys and values again

$a = array_flip($a);

//Reorder array keys

$a = array_values($a);

//Output updated array

Echo "Update array:";

var_dump($a);

?>

Output:

Original array:

Array (size=0)

0 => int 1

1 => int 5

2 => int 2

3 => int 5

4 => int 1

5 => int 3

6 => int 2

7 => int 4

8 => int 5

Update array:

Array (size=5)

0 => int 1

1 => int 5

2 => int 2

3 => int 5

4 => int 1

The above is the details of how PHP deletes duplicate elements in an array.

Source of this article Shangpin China: Enterprise website construction