What is the method to obtain the intersection and difference of arrays in php

1. Intersection of arrays array_intersect()

array_intersect() function returns an array with retained keys, This array consists only of values ​​that appear in the first array and appear in every other input array. Its form is as follows:

array array_intersect(array array1,array array2[,arrayN…])

The following example will return all the fruits that appear in the $fruit1 array and also appear in $fruit2 and $fruit3:

<?php
$fruit1 = array("Apple","Banana","Orange");
$fruit2 = array("Pear","Apple","Grape");
$fruit3 = array("Watermelon","Orange","Apple");
$intersection = array_intersect($fruit1, $fruit2, $fruit3);
print_r($intersection);
// output
// Array ( [0] => Apple )
?>

Only in the two elements Only when they are equal and have the same data type, the array_intersect() function will consider them to be the same.

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Intersection of associative arrays array_intersect_assoc()

Function array_intersect_assoc() and array_intersect () is basically the same, except that it also considers the keys of the array in the comparison. Therefore, only key/value pairs that appear in the first array and also appear in all other input arrays are returned in the result array.

The form is as follows:

array array_intersect_assoc(array array1,array array2[,arrayN…])

The following example returns all key/value pairs that appear in the $fruit1 array and also appear in $fruit2 and $fruit3:

<?php
$fruit1 = array("red"=>"Apple","yellow"=>"Banana","orange"=>"Orange");
$fruit2 = array("yellow"=>"Pear","red"=>"Apple","purple"=>"Grape");
$fruit3 = array("green"=>"Watermelon","orange"=>"Orange","red"=>"Apple");
$intersection = array_intersect_assoc($fruit1, $fruit2, $fruit3);
print_r($intersection);
// output
// Array ( [red] => Apple )
?>

2. Array difference array_diff()

Function array_diff() returns values ​​that appear in the first array but are not in other input arrays. This function is the opposite of array_intersect().

array array_diff(array array1,array array2[,arrayN…])

The examples are as follows:

<?php
$fruit1 = array("Apple","Banana","Orange");
$fruit2 = array("Pear","Apple","Grape");
$fruit3 = array("Watermelon","Orange","Apple");
$intersection = array_diff($fruit1, $fruit2, $fruit3);
print_r($intersection);
// output
// Array ( [1] => Banana )
?>

The difference set of associative array array_diff_assoc()

The function array_diff_assoc() is basically the same as array_diff(), except that it The keys of the array are also taken into account when comparing. Therefore, only key/value pairs that appear in the first array but not in the other input arrays are returned in the result array. Its form is as follows:

array array_diff_assoc(array array1,array array2[,arrayN…])

The following example only returns [yellow] => Banana, because this special key/value pair appears in $fruit1, but does not exist in $fruit2 and $fruit3 .

<?php
$fruit1 = array("red"=>"Apple","yellow"=>"Banana","orange"=>"Orange");
$fruit2 = array("yellow"=>"Pear","red"=>"Apple","purple"=>"Grape");
$fruit3 = array("green"=>"Watermelon","orange"=>"Orange","red"=>"Apple");
$intersection = array_diff_assoc($fruit1, $fruit2, $fruit3);
print_r($intersection);
// output
// Array ( [yellow] => Banana )
?>

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