PHP合并两个数组的两种方式的异同

特别是+运算符，他的意思是，将右边的数组单元（去重复）追加到左边数组的后面。
复制代码代码如下:
<？php
echo " 第一种情况 ";
$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 " 第二种情况 ";
$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 " 第三种情况 ";
$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）;
？>

结果如下：
复制代码代码如下:
第一种情况
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
）
第二种情况
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
）
第三种情况
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
）