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 $b will 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

##array_intersect_assoc

##Related learning recommendations:

PHP programming from entry to proficient

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