+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

+

$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

+

array_merge()

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。