php合并数组的两种方式

1：+

2：array_merge()函数

加号形式，不管是索引数组还是关联数组，如果出现key一样的时候，以前一个数组的值为准，例如：

$a = array('a'=>'1','b'=>'2','c'=>'3');  
$b = array('c'=>3,'d'=>'4','e'=>'5'); 
$c = $a+$b; 
var_dump($c);

array (size=5)  'a' => string '1' (length=1)  'b' => string '2' (length=1)  'c' => string '3' (length=1)  'd' => string '4' (length=1)  'e' => string '5' (length=1)

$a = array(1=>'one',2=>'two',3=>'three1');  
$b = array(3=>'three2',4=>'four',5=>'five');  
$c = $a+$b; 
var_dump($c);

array (size=5)  1 => string 'one' (length=3)  2 => string 'two' (length=3)  3 => string 'three1' (length=6)  4 => string 'four' (length=4)  5 => string 'five' (length=4)

array_merge()形式，如果是关联数组，key相同的情况下，以后一个数组的值为准(也就是后一个的值会覆盖掉前一个值)，如果是索引数组，则不会覆盖，会增加一个key,例如

$a = array('a'=>'1','b'=>'2','c'=>'3');  
$b = array('c'=>3,'d'=>'4','e'=>'5'); 
$d = array_merge($a,$b); 
var_dump($d);

array (size=5)  'a' => string '1' (length=1)  'b' => string '2' (length=1)  'c' => int 3  'd' => string '4' (length=1)  'e' => string '5' (length=1)

$a = array(1=>'one',2=>'two',3=>'three1');  
$b = array(3=>'three2',4=>'four',5=>'five');  
$d = array_merge($a,$b); 
var_dump($d);

array (size=6)  0 => string 'one' (length=3)  1 => string 'two' (length=3)  2 => string 'three1' (length=6)  3 => string 'three2' (length=6)  4 => string 'four' (length=4)  5 => string 'five' (length=4)