Level 16
public function fact(int $n) {
return ($n >= 1) ? ($n * $this->fact($n - 1)) : 1;
}
1 like
Aug 23, 2020
11
Level 4
Recursive ♻️Factorial
Hello again! 👋🏻
This code I have written and understood. The idea came to me when I tried to solve it with a "for" loop.
Is that a "clean code"? I've heard about recursion many times, but until now I didn't call the function again and again, because the thing with the "Allowed memory size" without the if-block scared me! 👻
Thanks! 💜
function recursive_factorial($int) {
if ($int == 0) {
return 1;
}
return recursive_factorial($int-1) * $int;
}
print_r(recursive_factorial(5)); // 1 * 2 * 3 * 4 * 5
120
Level 75
@ravish What's the difference from his code?
A recursive function is a function that calls itself. If the function keeps calling itself, how does it know when to stop? You have to set up a condition, known as a base case. Base cases tell our recursive call when to stop, otherwise it will loop infinitely.
1 like
Level 16
@michaloravec How will my function keep looping infinitely? The condition is already set. It works just fine. And there is no difference between his and mine function, I just wrote it in less lines.
1 like
Level 75
@ravish What I posted is a generel thing what has to be done in the recursive function.
The question for you was why you posted that, when it's the same.
Level 4
Hello friends!
The more code, the better, even if it is not the same code, right?
What @ravish posted seems to me to be a method in a class, while mine is a function. But of course the same in principle.
The question was whether the recursion itself is "clean code". :)
Level 75
@konstruktionsplan Why shouldn't it be?
Level 4
"I've heard about recursion many times, but until now I didn't call the function again and again, because the thing with the "Allowed memory size" without the if-block scared me!"
If I don't catch an error somewhere, it will crash on a live server, but it will not paralyze it. But if I start an "infinite call", it will crash much more, right?
Level 102
You will just get this error :)
Error
Maximum function nesting level of '256' reached, aborting!
Give it a try yourself
Route::get('recurse', function () {
function myrecurse() {
return myrecurse();
}
return myrecurse();
});
1 like
Level 4
Hey @sinnbeck
But only in Laravel, right? Plain PHP wouldn't catch that? 🤔
Level 75
No, it depends what you have set in php.ini for max_nesting_level
It's a PHP related things.
1 like
Level 102
I actually believe that it is xdebug that catches it :) You can give it a try on your local testing environment. Without xdebug you would most likely just run out of memory and the thread would be closed.
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