php array_merge 与 + 处理相同数组键名 的区别

相同数组键名为数字时

• + 会保留最先出现的那个值
• array_merge 会附加到后面

 $a = [1,2,3];
 $b = [11,22,33];
 print_r($a+$b);
 print_r(array_merge($a,$b));

//输出结果为

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
)
Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 11
    [4] => 22
    [5] => 33
)

相同数组键名为字符时

• + 会保留最先出现的那个值
• array_merge 会覆盖掉前面相同键名的值

 $a = ['a'=>1,'b'=>2,'c'=>3];
 $b = ['a'=>11,'b'=>22,'c'=>33];
print_r($a+$b);
print_r(array_merge($a,$b));

//输出结果为
Array
(
    [a] => 1
    [b] => 2
    [c] => 3
)
Array
(
    [a] => 11
    [b] => 22
    [c] => 33
)