Php array_intersect is faster than array_diff (with detailed instructions)

If the number of difference sets between array $ a and array $ B is required, use count ($ a)-count (array_intersect ($ a, $ B )), instead of using count (array_diff ($ a, $ B ));

The front is faster than the latter, and more obvious in the large array.

1. array_intersect Function
Array array_intersect (array $ array1, array $ array2 [, array $...])
Array_intersect () returns an array containing all values that appear in the array of all other parameters at the same time in array1. Note that the key name remains unchanged.
#1 array_intersect () Example
Copy codeThe Code is as follows:
<? Php
$ Array1 = array ("a" => "green", "red", "blue ");
$ Array2 = array ("B" => "green", "yellow", "red ");
$ Result = array_intersect ($ array1, $ array2 );
?>
This makes $ result:
Array
(
[A] => green
[0] => red
)

2. Self-implemented array_intersect () functions are five times faster than the original php function array_intersect ().
Copy codeThe Code is as follows:
/**
*
* Custom array_intersect
* If the result is the intersection of one-dimensional arrays, this function is five times faster than the system's array_intersect.
*
* @ Param array $ arr1
* @ Param array $ arr2
* @ Author LIUBOTAO 2010-12-13 11:40:20 AM
*
*/
Function my_array_intersect ($ arr1, $ arr2)
{
For ($ I = 0; $ I <sizeof ($ arr1); $ I ++)
{
$ Temp [] = $ arr1 [$ I];
}
For ($ I = 0; $ I <sizeof ($ arr1); $ I ++)
{
$ Temp [] = $ arr2 [$ I];
}
Sort ($ temp );
$ Get = array ();
For ($ I = 0; $ I <sizeof ($ temp); $ I ++)
{
If ($ temp [$ I] ==$ temp [$ I + 1])
$ Get [] = $ temp [$ I];
}
Return $ get;
}
$ Array1 = array ("green", "red", "blue ");
$ Array2 = array ("green", "yellow", "red ");
Echo "<pre> ";
Print_r (my_array_intersect ($ array1, $ array2 ));
Echo "<pre/> ";

Array_diff-calculate the difference set of the array

Array array_diff (array $ array1, array $ array2 [, array $...])
Array_diff () returns an array containing all values in the array of array1 but not in any other parameter. Note that the key name remains unchanged.

#1 array_diff () Example
Copy codeThe Code is as follows:
<? Php
$ Array1 = array ("a" => "green", "red", "blue", "red ");
$ Array2 = array ("B" => "green", "yellow", "red ");
$ Result = array_diff ($ array1, $ array2 );
Print_r ($ result );
?>

The output result is as follows:
Copy codeThe Code is as follows:
Array
(
[1] => blue
)

Note: The two units are considered the same only when (string) $ elem1 === (string) $ elem2. That is to say, when the expression of the string is the same.

Note: This function only checks one dimension in a multi-dimensional array. Of course, you can use array_diff ($ array1 [0], $ array2 [0]); to check deeper dimensions.