Why does PHP sum values of similar array items differently?

Why does PHP sum values of similar array items differently?

To understand why PHP sums values of similar array items differently, we need to first clarify some concepts related to arrays and numerical operations in PHP.

In PHP, arrays are associative or indexed. When we talk about summing values of similar array items, we usually mean indexed arrays. In an indexed array, each element is identified by an index, which is a number.

Now, let's discuss numerical operations in PHP. PHP supports various arithmetic operators like +, -, *, /, and %. When we use these operators on numbers, PHP performs the operation directly. However, when we use these operators on arrays, PHP behaves differently depending on the context.

When we use the + operator on two numbers, PHP returns the sum of those numbers. But when we use the same + operator on two arrays, PHP performs array merging. Array merging is a process of combining two or more arrays into a single array, where the keys from both arrays are merged, and the values of the overlapping keys are merged recursively.

To sum the values of similar array items, we need to use a different approach. We can use the array_sum() function, which is specifically designed for this purpose. This function accepts an array as an argument and returns the sum of all the numerical values in that array.

So, the reason why PHP sums values of similar array items differently is due to the way it handles numerical operations on arrays. The + operator performs array merging instead of summing, and to sum the values of similar array items, we need to use the array_sum() function.

Here's an example to illustrate the concept:

$array1 = [1, 2, 3, 4, 5];
$array2 = [1, 2, 3, 4, 5];

// Using the + operator on two arrays will perform array merging
$mergedArray = $array1 + $array2;
print_r($mergedArray); // [1, 2, 3, 4, 5, 1, 2, 3, 4, 5]

// To sum the values of similar array items, use the array_sum() function
$sum = array_sum($array1);
print_r($sum); // Output: 15

In the example above, we have two arrays, $array1 and $array2, with identical elements. When we use the + operator on these arrays, PHP performs array merging, resulting in a new array with duplicate keys. However, when we use the array_sum() function on $array1, PHP returns the sum of all the numerical values in the array, which is 15.