php сравнение массивов по ключам
array_diff
(PHP 4 >= 4.0.1, PHP 5, PHP 7, PHP 8)
array_diff — Вычислить расхождение массивов
Описание
Список параметров
Массивы, с которыми идёт сравнение
Возвращаемые значения
Примеры
Пример #1 Пример использования array_diff()
Пример #2 Пример использования array_diff() с несовпадающими типами
$source = [new S ( ‘a’ ), new S ( ‘b’ ), new S ( ‘c’ )];
$filter = [new S ( ‘b’ ), new S ( ‘c’ ), new S ( ‘d’ )];
Примечания
Смотрите также
User Contributed Notes 27 notes
array_diff(A,B) returns all elements from A, which are not elements of B (= A without B).
You should include this in the documentation more precisely, I think.
array_diff provides a handy way of deleting array elements by their value, without having to unset it by key, through a lengthy foreach loop and then having to rekey the array.
If you want a simple way to show values that are in either array, but not both, you can use this:
I´ve been looking for a array_diff that works with recursive arrays, I´ve tried the ottodenn at gmail dot com function but to my case it doesn´t worked as expected, so I made my own. I´ve haven´t tested this extensively, but I´ll explain my scenario, and this works great at that case 😀
We got 2 arrays like these:
I realy hopes that this could help some1 as I´ve been helped a lot with some users experiences. (Just please double check if it would work for your case, as I sad I just tested to a scenario like the one I exposed)
I just came upon a really good use for array_diff(). When reading a dir(opendir;readdir), I _rarely_ want «.» or «..» to be in the array of files I’m creating. Here’s a simple way to remove them:
If you just need to know if two arrays’ values are exactly the same (regardless of keys and order), then instead of using array_diff, this is a simple method:
?>
The function returns true only if the two arrays contain the same number of values and each value in one array has an exact duplicate in the other array. Everything else will return false.
my alternative method for evaluating if two arrays contain (all) identical values:
?>
may be slightly faster (10-20%) than this array_diff method:
?>
but only when the two arrays contain the same number of values and then only in some cases. Otherwise the latter method will be radically faster due to the use of a count() test before the array_diff().
Also, if the two arrays contain a different number of values, then which method is faster will depend on whether both arrays need to be sorted or not. Two times sort() is a bit slower than one time array_diff(), but if one of the arrays have already been sorted, then you only have to sort the other array and this will be almost twice as fast as array_diff().
Basically: 2 x sort() is slower than 1 x array_diff() is slower than 1 x sort().
It’s important to note that array_diff() is NOT a fast or memory-efficient function on larger arrays.
In my experience, when I find myself running array_diff() on larger arrays (50+ k/v/pairs) I almost always realize that I’m working the problem from the wrong angle.
Typically, when reworking the problem to not require array_diff(), especially on bigger datasets, I find significant performance improvements and optimizations.
If you’re not getting a count(array_diff($a1,$a2))>0 with something similar to the following arrays should use the php.net/array_diff_assoc function instead.
There is more fast implementation of array_diff, but with some limitations. If you need compare two arrays of integers or strings you can use such function:
10x faster than array_diff
Here is some code to take the difference of two arrays. It allows custom modifications like prefixing with a certain string (as shown) or custom compare functions.
I always wanted something like this to avoid listing all the files and folders you want to exclude in a project directory.
$relevantFiles = array_diff(scandir(‘somedir’), array(‘.’, ‘..’, ‘.idea’, ‘.project));
As touched on in kitchin’s comment of 19-Jun-2007 03:49 and nilsandre at gmx dot de’s comment of 17-Jul-2007 10:45, array_diff’s behavior may be counter-intuitive if you aren’t thinking in terms of set theory.
array_diff() returns a *mathematical* difference (a.k.a. subtraction) of elements in array A that are in array B and *not* what elements are different between the arrays (i.e. those that elements that are in either A or B but aren’t in both A and B).
Drawing one of those Ven diagrams or Euler diagrams may help with visualization.
As far as a function for returning what you may be expecting, here’s one:
Resubmitting. the update for takes into account comparison issues
Computes the difference of all the arrays
I’ve found a way to bypass that. I had 2 arrays made of arrays.
I wanted to extract from the first array all the arrays not found in the second array. So I used the serialize() function:
Yes you can get rid of gaps/missing keys by using:
Note that array_diff is not equivalent to
The difference is made only on the first level. If you want compare 2 arrays, you can use the code available at https://gist.github.com/wrey75/c631f6fe9c975354aec7 (including a class with an function to patch the array)
Here the basic function:
A simple multidimentional key aware array_diff function.
Based on one lad’s code, I created following function for creating something like HTML diff. I hope it will be useful.
Hi!
I tried hard to find a solution to a problem I’m going to explain here, and after have read all the array functions and possibilities, I had to create what I think should exist on next PHP releases.
What I needed, it’s some kind of Difference, but working with two arrays and modifying them at time, not returning an array as a result with the diference itself.
so basically, I wanted to delete coincidences on both arrays.
Now, I’ve some actions to do, and I know wich one I’ve to do with the values from one array or another.
With the normal DIFF I can’t, because if I’ve an array like C=1,4, I dont know if I’ve to do the Action_A with 1 or with 4, but I really know that everything in A, will go to the Action_A and everithing in B, will go to Action_B. So same happens with 4, don’t know wich action to apply.
So a call to this will be somethin’ like:
Now, why I use it precisely?
Imagine you’ve some «Events» and some users you select when create the event, can «see» this event you create. So you «share» the event with some users. Ok?
Imagine you created and Event_A, and shared with users 1,2,3.
Now you want to modify the event, and you decide to modify the users to share it. Imagine you change it to users 2,3,4.
(numbers are users ID).
So you can manage when you are going to modify, to have an array with the IDs in DDBB ($original), and then, have another array with ID’s corresponding to the users to share after modifying ($new). Wich ones you’ve to DELETE from DDBB, and wich ones do you’ve to INSERT?
If you do a simple difference or somehow, you get somethin’ like C=1,4.
You have no clue on wich one you’ve to insert or delete.
But on this way, you can know it, and that’s why:
I hope you find it useful, and I encourage PHP «makers», to add in a not distant future, somethin’ like this one natively, because I’m shure that I’m not the first one needing something like this.