Use array_reduce() function in PHP to calculate the sum of array values

PHP is a programming language widely used in web development. It has many powerful functions, such as the array_reduce() function, which can be used to operate on values ​​in arrays. In this article, we will explain how to calculate the sum of array values ​​using the array_reduce() function.

First, let us understand the usage of array_reduce() function. This function accepts three parameters: an array, a callback function, and an initial value.

The callback function specifies the operation on the array elements. Its first parameter is the result of the previous iteration, and the second parameter is the current array element. The callback function returns a value that will be used as the first parameter of the next iteration.

When using the array_reduce() function to calculate the sum of array values, the callback function needs to return the sum of the current value and the last accumulated result. This sum will be used as the result of the next accumulation. The final value returned is the sum of all elements.

The following is a sample code:

$array = array(1, 2, 3, 4, 5);

$sum = array_reduce($array, function($carry, $item) {
    return $carry + $item;
});

echo $sum;

The output of the code is 15, which is the sum of all elements in the array.

It is worth noting that the array_reduce() function can also accept an optional fourth parameter. This parameter specifies the starting value of the first parameter of the callback function. If this value is not specified, the first argument to the callback function on the first iteration will be the first element of the array, and the second argument will be the second element of the array.

Now that we have mastered the basic usage of the array_reduce() function, let us look at a more practical example.

Suppose we have a math test score table, stored in an array. Each student's grade is expressed as an integer. We need to calculate the average score of these scores and output the results.

The following is the code we can use:

$grades = array(85, 92, 76, 88, 95);

$average = array_reduce($grades, function($carry, $grade) {
    return $carry + $grade;
}) / count($grades);

echo "The average grade is: " . $average;

The output of the code is: The average grade is: 87.2.

In the above code, we first define an array $grades containing five grades. We then use the array_reduce() function to calculate the sum of the array elements and finally divide by the length of the array to get the average.

In short, the array_reduce() function is one of the very useful functions in PHP and can be used to operate on elements in an array. Its callback function can perform various operations on the elements within the array. In this article, we demonstrate how to use the array_reduce() function to calculate the sum and average of array values. These techniques are very useful in actual development.

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