Prime Factors in PHP
Compute the prime factors of a given natural number.
1  exercism fetch php primefactors

Prime Factors
Compute the prime factors of a given natural number.
A prime number is only evenly divisible by itself and 1.
Note that 1 is not a prime number.
Example
What are the prime factors of 60?
 Our first divisor is 2. 2 goes into 60, leaving 30.
 2 goes into 30, leaving 15.
 2 doesn't go cleanly into 15. So let's move on to our next divisor, 3.
 3 goes cleanly into 15, leaving 5.
 3 does not go cleanly into 5. The next possible factor is 4.
 4 does not go cleanly into 5. The next possible factor is 5.
 5 does go cleanly into 5.
 We're left only with 1, so now, we're done.
Our successful divisors in that computation represent the list of prime factors of 60: 2, 2, 3, and 5.
You can check this yourself:
 2 * 2 * 3 * 5
 = 4 * 15
 = 60
 Success!
Running the tests

Go to the root of your PHP exercise directory, which is
<EXERCISM_WORKSPACE>/php
. To find the Exercism workspace run1
% exercism debug  grep Workspace

Get PHPUnit if you don't have it already.

Execute the tests:
1
% ./phpunit.phar primefactors/primefactors_test.php
Source
The Prime Factors Kata by Uncle Bob http://butunclebob.com/ArticleS.UncleBob.ThePrimeFactorsKata
Submitting Incomplete Solutions
It's possible to submit an incomplete solution so you can see how others have completed the exercise.