Introduction to two methods of array merging in PHP and their differences_PHP Tutorial

Two methods of merging PHP arrays and their differences
If it is an associative array, it is as follows:

Copy the code The code is as follows:

$a = array(
'where' => 'uid=1',
'order' => 'uid',
);
$b = array(
' where' => 'uid=2',
'order' => 'uid desc',
);

1. array_merge, if two arrays If the same key exists, the latter one will overwrite the previous one

Copy the code The code is as follows:

$c = array_merge($a, $b);
var_export($c);//The result is the same as the original $b
$d = array_merge($b, $a);
var_export ($d);//The result is the same as the original $a

2. "+" operator, if the two arrays have the same key, the former one will overwrite the latter

Copy code The code is as follows:

$c = $a + $b;
var_export( $c);//The result is the same as the original $a
$d = $b + $a;
var_export($d);//The result is the same as the original $b

If it is a numerical index array, it is as follows:

Copy code The code is as follows:

$a = array(
1 => '1111111',
2 => '222222222'
);
$b = array(
4 => '33333333333',
1 = > '444444444'
);

1. array_merge. The effect is similar to the code foreach for each array element, and then push each element into a new stack

Copy code The code is as follows:

$c = array_merge($a, $b);
var_export($ c);
$d = array_merge($b, $a);
var_export($d);

Output:
array (
0 => '1111111',
1 => '222222222',
2 => '33333333333',
3 => '444444444',
)
array (
0 " +" operator. The effect is similar to the code foreach each array element, and then push each element into a new stack. If the same key already exists, it will not be processed



Copy code

The code is as follows:

$c = $a + $b; var_export($c);

$d = $b + $a;

var_export($d);


Output:
array (
1 => '1111111',
2 => '222222222' ,

4 => '33333333333',
)
array (
4 => '33333333333',
1 => '444444444',
2 => '222222222',
)



http://www.bkjia.com/PHPjc/325991.html
www.bkjia.com

truehttp: //www.bkjia.com/PHPjc/325991.htmlTechArticlePHP array merging two methods and their differences. If it is an associative array, as follows: Copy the code The code is as follows: $a = array ( 'where' = 'uid=1', 'order' = 'uid', ); $b = array( 'where' = 'uid=2', 'orde...