Menu
Possible Duplicate:
What’s quicker and better to determine if an array key exists in PHP?
suppose I want to store the list of friends I have on memcache. sometimes i need to search if a user is on my list and sometime i need to fetch all the list of friends.
would you rather
$friends[] = $friend
or
$friends[$friend] = 1;
the rationale is to save as much as ram as decently possible without penalizing speed. I didn't find any case study for php 5.3.8 that can help me on my little dilemma: under load, which is faster to perform?
array_key_exists or in_array? (ie: is foo a friend of bar?)
Also, sometimes i need to fetch the whole list of friends so i need to iterate the whole list in order to build an array of friends. not sure at all about the second method, since I don't know yet if there will be more array_search|array_key_exists|in_array or fetch of full friends list.
any idea?
814
Performance Considerations The takeaway is that isset() is actually faster than array_key_exists() because isset() is actually a language construct, not a function, so it doesn't incur the function call overhead. But both are quite fast, so you probably shouldn't choose one over the other for performance reasons.
The main difference between both the functions is that array_search() usually returns either key or index whereas in_array() returns TRUE or FALSE according to match found in search.
The array_key_exists() function checks an array for a specified key, and returns true if the key exists and false if the key does not exist.
PHP array_key_exists() FunctionThe array_key_exists() is an inbuilt function of PHP that is used to check whether a specific key or index is present inside an array or not. The function returns true if the specified key is found in the array otherwise returns false.
array_key_exists is much faster. array_search must traverse the whole array, so it is O(n). array_key_exists is a hash table lookup, so it is O(1).
See http://en.wikipedia.org/wiki/Big_O_notation if you are new to this concept.
Between array_key_exists and isset, though both are very fast [O(1)], isset is significantly faster. If this check is happening many thousands of times, you'd want to use isset.
It should be noted that they are not identical, though -- when the array key exists but the value is null, isset will return false and array_key_exists will return true. If the value may be null, you need to use array_key_exists.
133
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
