PHP method to use callback function to given array cell

This article mainly introduces the method of PHP applying callback function to a given array unit. It is a very important application. Friends who need it can refer to it

Arrays are a very important part of PHP programming. This article introduces the usage of the array function array_map() in PHP to apply the callback function to a given array unit. The details are as follows:

array array_map ( callable $callback , array $arr1 [, array $... ] )

array_map() returns an array that contains all units in arr1 after callback has been applied.

The number of arguments accepted by callback should be consistent with the number of arrays passed to the array_map() function.

The sample program is as follows:

function fun($n)
{
 return $n * $n * $n;
}

$a = array(1, 2, 3, 4, 5);
$b = array_map('fun', $a); /* 每个数组单元作三次方运算，返回数组 */
print_r($b);

The output result is:

Array
(
 [0] => 1
 [1] => 8
 [2] => 27
 [3] => 64
 [4] => 125
)

In addition, the array_map() function has the following uses:

array_map('unlink', glob('*.txt'));/* glob返回"文件名.txt"组成的数组，然后对每个文件进行删除操作*/

array_map('unlink', glob('*.*'));

array_map('unlink', glob('*'));

If array_map() is not used, the only way to operate on each unit of the array is to traverse and assemble it appropriately.

The above is the detailed content of PHP method to use callback function to given array cell. For more information, please follow other related articles on the PHP Chinese website!