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In PHP, end() and array_key_last() are commonly used functions, and they have different uses when processing arrays. end() is used to get the last element of the array, while array_key_last() is used to get the last element of the array. These two functions have different performance in different scenarios, but they have some differences in performance and semantics. This article will comprehensively compare these two functions to help you make more appropriate choices in development.
The end() function is a very common array function in PHP. Its function is to point the internal pointer of the array to the last element of the array and return the value of that element. It should be noted that end() will change the internal pointer of the array, which means that if you manipulate the array again after calling end() , the position of the pointer will be affected.
$array = [1, 2, 3, 4, 5];
$lastElement = end($array);
echo $lastElement; // Output：5
The implementation of end() essentially takes the last element of the array by moving the internal pointer, so its performance is related to the size of the array and the position of the internal pointer. For ordinary arrays, the time complexity of end() is O(1), that is, its execution time has nothing to do with the length of the array. But if the array is large or requires multiple calls to end() , it may cause some performance losses, because each call to end() will change the position of the internal pointer.
The array_key_last() function was introduced in PHP 7.3.0. Its function is to return the key of the last element in the array. Unlike end() , array_key_last() does not change the internal pointer of the array, so it is safer, especially in scenarios where pointer position needs to be kept.
$array = [1 => 'a', 2 => 'b', 3 => 'c'];
$lastKey = array_key_last($array);
echo $lastKey; // Output：3
The implementation of the array_key_last() function directly obtains the last key through the structure of the array, so its performance can also be regarded as O(1) and does not change the internal pointer of the array. Therefore, in terms of performance, array_key_last() is more efficient than end() , especially when it is necessary to frequently get the last key of the array without changing the array pointer.
From a performance perspective, the time complexity of end() and array_key_last() are both O(1), and in theory, their performance differences are not significant in most cases. However, array_key_last() returns the last key without changing the array pointer, which makes it more efficient when it requires frequent manipulation of the array. If you do not need to manipulate the value of the array but only need to get the key, using array_key_last() is undoubtedly a more suitable choice.
Semantically, end() and array_key_last() have very different uses. end() mainly focuses on the last element of the array, while array_key_last() focuses more on returning the key of the last element in the array. This difference makes them have different application scenarios in different scenarios.
end() : works for scenarios where you care about the last value in the array and don't mind changing the array pointer.
array_key_last() : works when you only care about the keys of the last element of the array and want to avoid changing the internal pointer.
The choice of end() or array_key_last() depends on your specific needs. If your code logic needs to get the value of the array and can accept modifying the position of the array pointer, end() is a more common choice. But if you only need to get the key of the last element and don't want to affect other operations of the array, array_key_last() will be a better and safer choice.
Performance : Both have roughly the same performance, both O(1), but array_key_last() is more efficient, especially without changing the array pointer.
Semantics : end() focuses on getting the last element of the array, while array_key_last() focuses on getting the key of the last element of the array.
Usage scenario : Choose according to your needs. If you need a value and don’t mind changing the pointer, use end() ; if you only need a key and want to maintain the pointer position, use array_key_last() .
I hope this article can help you make more appropriate choices in PHP and improve the performance and readability of your code.
