PHP 求解数组的交集或者差集

古城微笑少年丶 2024-04-03 09:44 52阅读 0赞

一、数组的交集 array\_intersect()

> 1.1 array\_intersect()

1.  `函数返回一个保留了键的数组，这个数组只由第一个数组中出现的且在其他每个输入数组中都出现的值组成。`

其形式如下：

> 1.  `array array_intersect(array array1,array array2[,arrayN…])`

示例

> 1.  `$fruit1 = array("Apple","Banana","Orange");`
> 2.  `$fruit2 = array("Pear","Apple","Grape");`
> 3.  `$fruit3 = array("Watermelon","Orange","Apple");`
> 4.  `$intersection = array_intersect($fruit1, $fruit2, $fruit3);`
> 5.  `print_r($intersection);`
> 6.  
> 7.  `// Array ( [0] => Apple )`

**只有在两个元素相等且具有相同的数据类型时，array\_intersect()函数才会认为它们是相同的。**

1.2 array\_intersect\_assoc()

> 1.  `函数array_intersect_assoc()与array_intersect()基本相同，只不过他在比较中还考虑了数组的键。`
> 2.  `因此，只有在第一个数组中出现，且在所有其他输入数组中也出现的键/值对才返回到结果数组中。`

形式如下：

> 1.  `array array_intersect_assoc(array array1,array array2[,arrayN…])`

示例:

> 1.  `$fruit1 = array("red"=>"Apple","yellow"=>"Banana","orange"=>"Orange");`
> 2.  `$fruit2 = array("yellow"=>"Pear","red"=>"Apple","purple"=>"Grape");`
> 3.  `$fruit3 = array("green"=>"Watermelon","orange"=>"Orange","red"=>"Apple");`
> 4.  `$intersection = array_intersect_assoc($fruit1, $fruit2, $fruit3);`
> 5.  `print_r($intersection);`
> 6.  `// output`
> 7.  `// Array ( [red] => Apple )`

二、数组的差集

2.1 array\_diff()

> 1.  `函数array_diff()返回出现在第一个数组中但其他输入数组中没有的值。`
> 2.  `这个功能与array_intersect()相反。`

形式如下：

> 1.  `array array_diff(array array1,array array2[,arrayN…])`

示例:

> 1.  `$fruit1 = array("Apple","Banana","Orange");`
> 2.  `$fruit2 = array("Pear","Apple","Grape");`
> 3.  `$fruit3 = array("Watermelon","Orange","Apple");`
> 4.  `$intersection = array_diff($fruit1, $fruit2, $fruit3);`
> 5.  `print_r($intersection);`
> 6.  `// output`
> 7.  `// Array ( [1] => Banana )`

2.2 array\_diff\_assoc()

> 1.  `函数array_diff_assoc()与array_diff()基本相同，只是它在比较时还考虑了数组的键。`
> 2.  `因此，只在第一个数组中出现而不再其他输入数组中出现的键/值对才会返回到结果数组中。`

其形式如下：

> 1.  `array array_diff_assoc(array array1,array array2[,arrayN…])`

示例:

> 1.  `$fruit1 = array("red"=>"Apple","yellow"=>"Banana","orange"=>"Orange");`
> 2.  `$fruit2 = array("yellow"=>"Pear","red"=>"Apple","purple"=>"Grape");`
> 3.  `$fruit3 = array("green"=>"Watermelon","orange"=>"Orange","red"=>"Apple");`
> 4.  `$intersection = array_diff_assoc($fruit1, $fruit2, $fruit3);`
> 5.  `print_r($intersection);`
> 6.  `// output`
> 7.  `// Array ( [yellow] => Banana )`