Example: I have an array with 3 values:
0 = 1
1 = 4
2 = 5
I want to get a random number like
$random = rand(1, 5);
But I need to get a number that is different from the array values. I need it to return 2 or 3.
1 Answer
This should work for you:
(Here I create the range from where you get your random number with range(). Then I get rid of these numbers which you don't want with array_diff(). And at the end you can simply use array_rand() to get a random key/number)
<?php
$blacklist = [1, 4, 5];
$range = range(1, 5);
$randomArray = array_diff($range, $blacklist);
echo $randomArray[array_rand($randomArray, 1)];
?>
output:
2 or 3
EDIT:
Just did some benchmarks and the method with the loop is much slower than the code above!
I created an array(blacklist) from 1...100'000 and a random number array from 1... 100'001.
So that script should only create one/unique random number. With the loop method you get an error:
Fatal error: Maximum execution time of 30 seconds exceeded
And with the posted code above it takes 1.5 sec in average.
6 Comments
Barmar
This is much nicer than the loop, it shouldn't cause a time exceeded error.
Rizier123
@Barmar Thanks, That's why I posted it when I saw the possible dupe, since there were no such answer.
Rizier123
@Barmar Just did some benchmarks and it's a huge difference! (see updated answer)
Rockman
@Rizier123 Thanks again! It worked just fine, and it is really what i was looking for. I didn't know this array_diff.
Rockman
I accepted now, I guess... This was my first question here in stackoverflow, i'm still learning how to use it, hehe.
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do { $random = rand(1, 5); } while (in_array($random, $myArray));