PHP native function realizes the maximum value in the array

In PHP programming, array is a very common data type. In some cases we need to find the maximum or minimum value in an array. Although PHP has provided a series of functions to accomplish this task, such as the max() and min() functions. However, in some specific cases, native functions need to be used to accomplish this task.

This article will introduce how to use PHP native functions to find the maximum value in an array.

1. Native functions

First, we need to understand two native functions: array_shift() and array_reduce(). Both functions are very commonly used in PHP.

a. array_shift()

The array_shift() function is used to remove the first element from the array and delete the first element from the original array. Its syntax is as follows:

mixed array_shift ( array &$array )

Input parameter description:

$array: the array to be operated on.

Return value description:

The first element taken out, if the array is empty, NULL is returned.

For example:

$array = [1, 2, 3, 4, 5];
$first_element = array_shift($array);  // $first_element = 1

After execution, the original array becomes:

$array = [2, 3, 4, 5];

b. array_reduce()

array_reduce() function is used for iteration array and accumulate its elements through the callback function. Its syntax is as follows:

mixed array_reduce ( array $array , callable $callback [, mixed $initial = NULL ] )

Input parameter description:

$array: the array to be iterated.

$callback: Callback function used to accumulate each element.

$initial: Optional, passed in as the first parameter of the callback function.

Return value description:

The calculation result after the callback function is applied to all elements.

For example:

$array = [1, 2, 3, 4, 5];
$sum = array_reduce($array, function($carry, $item) {
    return $carry + $item;
}, 0);  // $sum = 15

2. Implementation process

Now that we have understood the native functions, we can use these functions to find the maximum value in an array . The specific process is as follows:

a. Initialize the $max variable to the first element of the array

Use the array_shift() function to take out the first element of the array as the $max variable, so that we can Use this variable as the initial maximum value.

$max = array_shift($array);

b. Iterate the array and find the maximum value through the array_reduce() function

We can use the array_reduce() function to iterate the array and compare each element with the $max variable, if If the element is greater than $max, update $max to that element. Finally, $max is returned as the maximum value in the array.

$max = array_reduce($array, function($carry, $item) {
    if ($item > $carry) {
        return $item;
    }
    return $carry;
}, $max);

c. Complete code

In order to understand the above process more clearly, the following is a complete code example:

3. Summary

In PHP programming, we usually use the built-in functions max() and min() to find the maximum and minimum values ​​of an array. However, in some cases these functions may not be the optimal solution. This article introduces the use of PHP native functions array_shift() and array_reduce() to find the maximum value of an array. These functions are very powerful tools that allow us to solve problems with more flexibility.

The above is the detailed content of PHP native function realizes the maximum value in the array. For more information, please follow other related articles on the PHP Chinese website!