![]() ![]() ![]() The bucket is then searched iteratively until the exact key is found in O(n).īarring any intentional hash collisions, this approach yields much better performance than in_array(). The key is hashed first using the djb hash function to determine the bucket of similarly hashed keys in O(1). Using isset() takes advantage of speedier lookup because it uses a hash table, avoiding the need for O(n) searches. $total_time = microtime( true ) - $start Įcho "Total time: ", number_format($total_time, 6), PHP_EOL All random, so beware that times will fluctuate. This builds on Jason's benchmark by filling in some random values and occasionally finding a value that exists in the array. ![]() These can be demonstrated by using an array with values (10,000 in the test below), forcing in_array to do more searching. Being an opcode, it has less overhead than calling the in_array built-in function.It uses an O(1) hash search on the key whereas in_array must check every value until it finds a match.Using isset in this case is faster because it can still cause collisions, but would take away from a possible DoS attack when reading from a user provided file ( ) I was wondering what is faster between those two examples keeping in mind that the array's keys in my case are not important (pseudo-code naturally): Īs the point of the question is not the array collision, I would like to add that if you are afraid of colliding inserts for $a, you can use $a. I looked around and I was not able to find an answer. This question is merely for me as I always like to write optimized code that can run also on cheap slow servers (or servers with A LOT of traffic) ![]()
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