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Array_merge program to merge two arrays in PHP_PHP tutorial

WBOYOriginal: 2016-07-13 17:14:58814browse

In php, we use the array_merge() function to merge data. The array_merge() function merges two or more arrays into one array. If there are duplicate key names, the key value of the key will be the value corresponding to the last key name (the later one will overwrite the previous one). If the array is numerically indexed, the key names are re-indexed consecutively.

The code is as follows

Copy code

echo "rnFirst case rn";
$a=array(1,2,3,4,5,6);
$b=array(7,8,9);

$c=array_merge ($a,$b);
print_r($c);
$c=$a+$b;
print_r($c);
$c=$b+$a;
print_r($c);

echo "rnSecond case rn";
$a=array('a','b','c','d','e','f');
$b=array('a','x','y');

$c=array_merge ($a,$b);
print_r($c);
$c=$a+$b;
print_r($c);
$c=$b+$a;
print_r($c);

echo "rnThe third case rn";

$a=array(
1=>'a',
2=>'b',
3=>'c',
4=>'d',
5=>'e',
6=>'f');
$b=array(
1=>'a',
7=>'x',
8=>'y');

$c=array_merge ($a,$b);
print_r($c);
$c=$a+$b;
print_r($c);
$c=$b+$a;
print_r($c);
?>

The results are as follows:

The first situation
Array
(
[0] => 1
[1] => 2
[2] => 3
[3] => 4
[4] => 5
[5] => 6
[6] => 7
[7] => 8
[8] => 9
)
Array
(
[0] => 1
[1] => 2
[2] => 3
[3] => 4
[4] => 5
[5] => 6
)
Array
(
[0] => 7
[1] => 8
[2] => 9
[3] => 4
[4] => 5
[5] => 6
)

The second situation
Array
(
[0] => a
[1] => b
[2] => c
[3] => d
[4] => e
[5] => f
[6] => a
[7] => x
[8] => y
)
Array
(
[0] => a
[1] => b
[2] => c
[3] => d
[4] => e
[5] => f
)
Array
(
[0] => a
[1] => x
[2] => y
[3] => d
[4] => e
[5] => f
)

The third situation
Array
(
[0] => a
[1] => b
[2] => c
[3] => d
[4] => e
[5] => f
[6] => a
[7] => x
[8] => y
)
Array
(
[1] => a
[2] => b
[3] => c
[4] => d
[5] => e
[6] => f
[7] => x
[8] => y
)
Array
(
[1] => a
[7] => x
[8] => y
[2] => b
[3] => c
[4] => d
[5] => e
[6] => f
)

1) Key name

When

is a number, array_merge() will not overwrite the original value, but +merging the array will return the first value as the final result, and "discard" those values in the subsequent arrays with the same key name. Remove (not cover)

2) When the key name is a character, + still returns the first value as the final result, and "discards" those values in the subsequent arrays with the same key name, but array_merge() will overwrite them at this time The value of the same key name before

Note: If only an array is input to the array_merge() function, and the keys are integers, the function will return a new array with integer keys, whose keys are re-indexed starting with 0

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