php 数组合并用加号(+)和用array_merge()的区别

小鱼儿 2022-05-17 08:19 157阅读 0赞

转载：[https://www.cnblogs.com/iLoveMyD/archive/2012/11/18/2775934.html][https_www.cnblogs.com_iLoveMyD_archive_2012_11_18_2775934.html]

结论:用加号合并数组:既考虑数字索引的键值对,也考虑字符串索引的键值对,用前边数组的值覆盖后边的键名相同的值;
    
    用array_merge()合并数组:只考虑字符串索引的键值对,用后边数组的值覆盖掉前面数组中键名相同的值,数字索引的值则不覆盖,同时保留
    
    另外:array_merge()会重排两个数组的数字索引,"+"则不会
    
     
    
    第一先看数组元素:
    
    复制代码
    <?php
    $a = array('r'=>1,2,3,4);
    var_dump('a',$a);
    $b = array('r'=>5,6,7,8);
    var_dump('b',$b);
    $c = array('r'=>5,6,7,8,9);
    var_dump('c',$c);
    
    var_dump('a+b',$a+$b);
    var_dump('a+c', $a+$c);
    
    var_dump('amb', array_merge($a, $b));
    var_dump('amc', array_merge($a, $c));
    复制代码
    第二看输出:
    
    复制代码
    string 'a' (length=1)
    array
      'r' => int 1
      0 => int 2
      1 => int 3
      2 => int 4
    string 'b' (length=1)
    array
      'r' => int 5
      0 => int 6
      1 => int 7
      2 => int 8
    string 'c' (length=1)
    array
      'r' => int 5
      0 => int 6
      1 => int 7
      2 => int 8
      3 => int 9
    
    string 'a+b' (length=3)
    array
      'r' => int 1
      0 => int 2
      1 => int 3
      2 => int 4
    
    string 'a+c' (length=3)
    array
      'r' => int 1
      0 => int 2
      1 => int 3
      2 => int 4
      3 => int 9
    
    string 'amb' (length=3)
    array
      'r' => int 5
      0 => int 2
      1 => int 3
      2 => int 4
      3 => int 6
      4 => int 7
      5 => int 8
    
    string 'amc' (length=3)
    array
      'r' => int 5
      0 => int 2
      1 => int 3
      2 => int 4
      3 => int 6
      4 => int 7
      5 => int 8
      6 => int 9
    复制代码

[https_www.cnblogs.com_iLoveMyD_archive_2012_11_18_2775934.html]: https://www.cnblogs.com/iLoveMyD/archive/2012/11/18/2775934.html