PHP数组反转

例1：

1 <?php
2 $a1=array("a"=>"1","b"=>"2","c"=>"3",1,array(1,2));
3 $result=array_reverse($a1);
4 print_r($result);
5 ?>

Array ( [0] => Array ( [0] => 1 [1] => 2 ) [1] => 1 [c] => 3 [b] => 2 [a] => 1 )

例2：

1 <?php
2 $a1=array("a"=>"1","b"=>"2","c"=>"3",1,array(1,2));
3 $result=array_reverse($a1,true);
4 print_r($result);
5 ?>

Array ( [1] => Array ( [0] => 1 [1] => 2 ) [0] => 1 [c] => 3 [b] => 2 [a] => 1 )

测试一下，preserve_keys如果写其它内容，会怎样。

1 <?php
2 $a1=array("a"=>"1","b"=>"2","c"=>"3",1,array(1,2));
3 $result=array_reverse($a1,1);
4 print_r($result);
5 ?>

Array ( [1] => Array ( [0] => 1 [1] => 2 ) [0] => 1 [c] => 3 [b] => 2 [a] => 1 )

如果preserve_keys为数字，效果跟true一样。

1 <?php
2 $a1=array("a"=>"1","b"=>"2","c"=>"3",1,array(1,2));
3 $result=array_reverse($a1,false);
4 print_r($result);
5 ?>

改成false，

Array ( [0] => Array ( [0] => 1 [1] => 2 ) [1] => 1 [c] => 3 [b] => 2 [a] => 1 )

与不填写一样。