[php合并2个数据库]PHP合并2个数字键数组的值的程序

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先要了解一个基础知识点

PHP中两个数组合并可以使用+或者array_merge，但之间还是有区别的，而且这些区别如果了解不清楚项目中会要命的！
主要区别是两个或者多个数组中如果出现相同键名，键名分为字符串或者数字，需要注意
1）键名为数字时，array_merge()后面的值将不会覆盖原来的值，而是附加到后面，但＋合并数组则会把最先出现的值作为最终结果返回，而把后面的数组拥有相同键名的那些值“抛弃”掉（不是覆盖）
2）键名为字符串时，array_merge()此时会覆盖掉前面相同键名的值，但＋仍然把最先出现的值作为最终结果返回，而把后面的数组拥有相同键名的那些值“抛弃”掉（不是覆盖）。

$a = array("a", "b");
$b = array("c", "d");
$c = $a + $b;
var_dump($a);
var_dump(array_merge($a, $b));

//输出：

array
  0 => string "a" (length=1)
  1 => string "b" (length=1)

array
  0 => string "a" (length=1)
  1 => string "b" (length=1)
  2 => string "c" (length=1)
  3 => string "d" (length=1)

++++++++++++++++++++++++++++++++++++++++++ 
 
$a = array(
 0 => "a",
 1 => "b"
);
$b = array(
 0 => "c",
 1 => "b"
);
$c = $a + $b;
var_dump($c);
var_dump(array_merge($a, $b));

//输出：

array
  0 => string "a" (length=1)
  1 => string "b" (length=1)

array
  0 => string "a" (length=1)
  1 => string "b" (length=1)
  2 => string "c" (length=1)
  3 => string "b" (length=1)

++++++++++++++++++++++++++++++++++++++++++ 

$a = array("a", "b");
$b = array(
 "0" => "c",
 1 => "b"
);
$c = $a + $b;
var_dump($c);
var_dump(array_merge($a, $b));

//输出：
array
  0 => string "a" (length=1)
  1 => string "b" (length=1)

array
  0 => string "a" (length=1)
  1 => string "b" (length=1)
  2 => string "c" (length=1)
  3 => string "b" (length=1)

++++++++++++++++++++++++++++++++++++++++++

$a = array(
 0 => "a",
 1 => "b"
);
$b = array(
 "0" => "c",
 "1" => "b"
);
$c = $a + $b;
var_dump($c);
var_dump(array_merge($a, $b));

输出：

array
  0 => string "a" (length=1)
  1 => string "b" (length=1)

array
  0 => string "a" (length=1)
  1 => string "b" (length=1)
  2 => string "c" (length=1)
  3 => string "b" (length=1)

好了讲到这么多了我们来看看下合并2个数字键数组的值

/**
 * PHP合并2个数字键数组的值
 *
 * @param array $arr1
 * @param array $arr2
 * @return array
 * @author www.111cn.net
 */
function new_array_merge($arr1, $arr2)
{
 $arr = array_flip($arr1) + array_flip($arr2);
 return array_keys($arr);
}

$arr1 = array("aa", "bb", "cc");
$arr2 = array("aa2", "bb", "cc2");

$arr = new_array_merge($arr1, $arr2);
print_r($arr);

输出：

Array
(
    [0] => aa
    [1] => bb
    [2] => cc
    [3] => aa2
    [4] => cc2
)

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