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This article introduces the knowledge of "how to apply the callback function to a given array unit by PHP". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

Array is a very important part of PHP programming. This article introduces the use 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 containing all the cells in the arr1 that have been acted on by callback.

The number of parameters accepted by callback should be the same as the number of arrays passed to the array_map () function.

The example program is as follows:

Function fun ($n) {return $n * $n * $n;} $a = array (1, 2, 3, 4, 5); $b = array_map ('fun', $a); / * each array unit performs cubic operations and returns the array * / print_r ($b)

The output is as follows:

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 returns an array of "filename .txt", and then deletes each file * / array_map ('unlink', glob (' *. *)); array_map ('unlink', glob (' *))

Without array_map (), each unit of the array can only be traversed and properly assembled.

That's all for "how PHP applies callback functions to a given array unit". Thank you for reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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