Analysis of the difference between array_merge PHP merge array + and array_merge

The main difference is that if the same key name appears in two or more arrays, the key name is divided into a string or a number. It should be noted that
1) When the key name is a number, array_merge() will not overwrite the original value, but + merge The array will return the first appearing value as the final result, and "abandon" those values ​​with the same key name in the subsequent arrays (not overwrite)
2) When the key name is a character, + still returns the first appearing value The value is returned as the final result, and those values ​​with the same key name in the subsequent array are "discarded", but array_merge() will overwrite the previous value with the same key name at this time
It should be noted that the array key format is 'number', etc. Value in numbers

Copy the code The code is as follows:

$a = array('a','b');
$b = array('c', 'd');
$c = $a + $b;
var_dump($a);
var_dump(array_merge($a, $b));
$a = array(0 => 'a', 1 => 'b');
$b = array(0 => 'c', 1 => 'b');
$c = $a + $b;
var_dump($c);
var_dump(array_merge($a, $b) );
$a = array('a', 'b');
$b = array('0' => 'c', 1 => 'b');
$c = $a + $ b;
var_dump($c);
var_dump(array_merge($a, $b));
$a = array(0 => 'a', 1 => 'b');
$b = array ('0' => 'c', '1' => 'b');
$c = $a + $b;
var_dump($c);
var_dump(array_merge($a, $b) ; 2 => string 'c' (length=1)
3 => string 'd' (length=1)

array
0 => string 'a' (length=1)
1 => string ' b' (length=1)

array 0 => string 'a' (length=1) 1 => string 'b' (length=1) 2 => string 'c' (length=1 ) 3 => string 'b' (length=1)

array

0 => string 'a' (length=1)
1 => string 'b' (length=1)
array
0 = > string 'a' (length=1)
1 => string 'b' (length=1)
2 => string 'c' (length=1)
3 => string 'b' (length =1)
array
0 => string 'a' (length=1)
1 => string 'b' (length=1)
array
0 => string 'a' (length=1)
1 => string 'b' (length=1)
2 => string 'c' (length=1)
3 => string 'b' (length=1)


The above introduces the analysis of the difference between array_merge PHP merge array + and array_merge, including the content of array_merge. I hope it will be helpful to friends who are interested in PHP tutorials.