+数组中的运算符在PHP中？

引用PHP语言操作员手册

+运算符返回添加到左侧数组的右侧数组；对于两个数组中都存在的键，将使用左侧数组中的元素，而右侧数组中的匹配元素将被忽略。

所以如果你这样做

$array1 = ['one', 'two', 'foo' => 'bar']; $array2 = ['three', 'four', 'five', 'foo' => 'baz'];

print_r($array1 + $array2); 你会得到

Array ( [0] => one // preserved from $array1 (left-hand array) [1] => two // preserved from $array1 (left-hand array) [foo] => bar // preserved from $array1 (left-hand array) [2] => five // added from $array2 (right-hand array) ) 因此，的逻辑+等效于以下代码段：

$union = $array1;

foreach ($array2 as $key => $value) { if (false === array_key_exists($key, $union)) { $union[$key] = $value; } } 如果您对C级实现的细节感兴趣，请访问

php-src / Zend / zend_operators.c 请注意，这+与array_merge()组合数组的方式不同：

print_r(array_merge($array1, $array2)); 会给你

Array ( [0] => one // preserved from $array1 [1] => two // preserved from $array1 [foo] => baz // overwritten from $array2 [2] => three // appended from $array2 [3] => four // appended from $array2 [4] => five // appended from $array2 ) 有关更多示例，请参见链接的页面。 问题来源于stack overflow