PHP array 的 加法操作

The + operator appends elements of remaining keys from the right handed array to the left handed, whereas duplicated keys are NOT overwritten.

今天 再次看 php manual的时候，才知道

代码

   
     

    
      
    
      <?
    
      php

    
      $a
    
       
    
      =
    
       
    
      array
    
      (
    
      "
    
      a
    
      "
    
       
    
      =>
    
       
    
      "
    
      apple
    
      "
    
      ,
    
       
    
      "
    
      b
    
      "
    
       
    
      =>
    
       
    
      "
    
      banana
    
      "
    
      );

    
      $b
    
       
    
      =
    
       
    
      array
    
      (
    
      "
    
      a
    
      "
    
       
    
      =>
    
       
    
      "
    
      pear
    
      "
    
      ,
    
       
    
      "
    
      b
    
      "
    
       
    
      =>
    
       
    
      "
    
      strawberry
    
      "
    
      ,
    
       
    
      "
    
      c
    
      "
    
       
    
      =>
    
       
    
      "
    
      cherry
    
      "
    
      );


    
      $c
    
       
    
      =
    
       
    
      $a
    
       
    
      +
    
       
    
      $b
    
      ; 
    
      //
    
       Union of $a and $b
    
      

    
      echo
    
       
    
      "
    
      Union of \
    
      $a
    
       and \
    
      $b
    
      : \n
    
      "
    
      ;

    
      var_dump
    
      (
    
      $c
    
      );


    
      $c
    
       
    
      =
    
       
    
      $b
    
       
    
      +
    
       
    
      $a
    
      ; 
    
      //
    
       Union of $b and $a
    
      

    
      echo
    
       
    
      "
    
      Union of \
    
      $b
    
       and \
    
      $a
    
      : \n
    
      "
    
      ;

    
      var_dump
    
      (
    
      $c
    
      );

    
      ?>
    
       

   
     

 

 



When executed, this script will print the following:

Union of $a and $b:
array(3) {
  ["a"]=>
  string(5) "apple"
  ["b"]=>
  string(6) "banana"
  ["c"]=>
  string(6) "cherry"
}
Union of $b and $a:
array(3) {
  ["a"]=>
  string(4) "pear"
  ["b"]=>
  string(10) "strawberry"
  ["c"]=>
  string(6) "cherry"
}
原来，我的理解就是。直接把$b中的元素直接复制到$a中。
我错了。