PHP merge arrays based on key value

Let’s now analyze how to merge two arrays and merge elements with the same key value together during the PHP development process.

Example 1

The simplest merge method

$a = [ 1=>'a', 2=>'b', 3=>'c' ]; $b = [ 3=>'e', 4=>'f', 5=>'c' ]; $c = $a+$b; print_r($c);

Output:

Array ( [1] => a [2] => b [3] => c [4] => f [5] => c )

Analysis:$ a[3]covers$b[3]. When there are elements with the same key value in the array, the previous array will be followed by the array elements with the same key value

Example 2

Using foreach loop assignment method

$a = [ 1=>'a', 2=>'b', 3=>'c' ]; $b = [ 3=>'e', 4=>'f', 5=>'a' ]; foreach ($b as $key => $val) { $a[$key] = $val; } print_r($a);

Output:

Array ( [1] => a [2] => b [3] => e [4] => f [5] => a )

Analysis: A little different from Example 1

Array used for looping$bwill overwrite the elements of the array$a, and only overwrite elements with the same key value

Related functions:

array_merge

array_intersect

##array_intersect_ukey

array_intersect_uassoc

array_intersect_key

##Related learning recommendations:

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