How to find remainder in php array

It is a very common operation to perform remainder (i.e. modulo operation) in PHP, especially when processing large amounts of data. PHP array is a very convenient data structure, which also contains some useful remainder functions. This article will introduce the operation of finding the remainder of a PHP array, as well as application scenarios and precautions.

1. Finding the remainder of a PHP array

In PHP, there are two main functions that can be used to find the remainder:

1. array_map() function

The array_map() function can pass the elements in one or more arrays to one or more functions one by one for processing, and return an array of processing results. We can define a custom function and pass it as a parameter to the array_map() function to perform the remainder operation on each array element.

The specific syntax is as follows:

array array_map ( callable $callback , array $array1 [, array $... ] )

The sample code is as follows:

$array = array(1, 2, 3, 4, 5);
$mod_array = array_map(function($num) {
    return $num % 3;
}, $array);
print_r($mod_array);

Output result:

Array
(
    [0] => 1
    [1] => 2
    [2] => 0
    [3] => 1
    [4] => 2
)

It can be seen that this function returns A new array in which each element is the remainder of the corresponding element in the original array.

2. array_walk() function

The array_walk() function applies a custom function to each value in an array without creating a new array. You can use this function to directly modify the values ​​in the original array.

The specific syntax is as follows:

bool array_walk ( array &$array , callable $callback [, mixed $userdata = NULL ] )

The sample code is as follows:

$array = array(1, 2, 3, 4, 5);
array_walk($array, function(&$num) {
    $num = $num % 3;
});
print_r($array);

Output result:

Array
(
    [0] => 1
    [1] => 2
    [2] => 0
    [3] => 1
    [4] => 2
)

It can be seen that this function is directly modified The value in the original array is changed, so that each element becomes the remainder of the corresponding element.

2. Application Scenarios

The application scenarios of PHP array remainder are very wide, especially when processing data.

For example, in data analysis, it is often necessary to perform a remainder operation on each data to facilitate better grouping or statistics in the next step. For another example, in website development, PHP arrays are often used to represent a large amount of data for operations such as data processing and display, among which finding the remainder is often a necessary operation.

3. Notes

Before using a PHP array to find the remainder, you need to pay attention to the following points:

1. The remainder operator in PHP is "%" .
2. When dealing with negative numbers, you need to pay attention to how to find the remainder, because PHP's remainder operator handles negative numbers differently.
3. When using the array_walk() function to modify the value of the original array, you need to use the "&" symbol to indicate that the passed parameter is a reference type.

Summary: Finding the remainder of a PHP array is a very basic operation, but it has a wide range of application scenarios. In actual programming, programmers should be proficient in the two functions for finding remainders in PHP arrays (array_map() and array_walk()) so that they can better perform operations such as data processing and display. At the same time, some details need to be paid attention to to avoid unnecessary errors.

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