How to check if two strings are anagrams in PHP?

PHP: How to check if two strings are anagrams in PHP?

This is a classic simple programming question. There are several ways to approach this problem. Here is one solution:

The comparison function:

  1. function is_anagram($a, $b)
  2. {
  3.  
  4.     if (strlen($a) != strlen($b)) {
  5.         // if not same size then they definitely aren't
  6.         return false;
  7.     }
  8.  
  9. // turn 'foobar' into ['f', 'o', 'o', 'b', 'a', 'r']
  10. $a_chars = str_split($a);
  11. $b_chars = str_split($b);
  12.  
  13. // sort them...
  14. sort($a_chars);
  15. sort($b_chars);
  16.  
  17. // check if they're exactly the same...
  18. return $a_chars === $b_chars;
  19.  
  20. // another way to do this that someone emailed me about, which is much more simple:
  21. // return (count_chars($a, 1) == count_chars($b, 1))
  22.  
  23.  
  24. }

Let's write some tests

  1. $anagrams = [
  2.  
  3.     // $a, $b, $is_valid_anagram
  4.  
  5.         ["asdf", "asdf", true],
  6.         ["asdf", "fdsa", true],
  7.         ["asdfasdf", "asdfasdf", true],
  8.         ["a", "a", true],
  9.         ["a", "b", false],
  10.         ["aaa", "aaa", true],
  11.         ["aaa", "aa", false],
  12.         ["aaaa", "abab", false],
  13.         ["qwerty", "asdfg", false]
  14.  
  15. ];

And now let's go through each one.

  1. foreach ($anagrams as $anagram) {
  2.  
  3.     [$a, $b, $is_valid_anagram] = $anagram;
  4.  
  5.     $result = is_anagram($a, $b);
  6.     $result_message = $result ? "Is an anagram" : "Is not an anagram";
  7.  
  8.     if ($result != $is_valid_anagram) {
  9.         throw new \Exception("The anagram function returned an incorrect result for $a and $b");  // this doesn't happen with our function! :)
  10.     }
  11.     var_dump("[$a] and [$b] $result_message");
  12.  
  13. }

"Our function said that [asdf] and [asdf] Is an anagram, which is correct"
"Our function said that [asdf] and [fdsa] Is an anagram, which is correct"
"Our function said that [asdfasdf] and [asdfasdf] Is an anagram, which is correct"
"Our function said that [a] and [a] Is an anagram, which is correct"
"Our function said that [a] and [b] Is not an anagram, which is correct"
"Our function said that [aaa] and [aaa] Is an anagram, which is correct"
"Our function said that [aaa] and [aa] Is not an anagram, which is correct"
"Our function said that [aaaa] and [abab] Is not an anagram, which is correct"
"Our function said that [qwerty] and [asdfg] Is not an anagram, which is correct"

BTW, not sure about how the [$a, $b, $is_valid_anagram] = $anagram; line works? See my blog post about array destructuring in PHP 7.

webdevetc profile pic
webdevetc

I am a 29 year old backend web developer from London, mostly focusing on PHP and Laravel lately. This (webdevetc.com) is my blog where I write about some web development topics (PHP, Laravel, Javascript, and some server stuff). contact me here.



More...

Comments and discussion about How to check if two strings are anagrams in PHP?
Found this interesting? Maybe you want to read some more in this series?
Or see other topics in the PHP language
Or see other languages/frameworks:
PHP Laravel Composer Apache CentOS and Linux Stuff WordPress General Webdev and Programming Stuff JavaScript
Or see random questions

What is the spaceship operator (<=>) in PHP?

How to check if two strings are anagrams in PHP?

How to fix the MySQL related "Specified key was too long error" error in Laravel

How to find out what version of Laravel you are using?

How to check if a string contains a certain substring?

How to order a Laravel hasMany relationship?

How to replace whitespace with a single space

What is an example of an object literal?

How to check if a relation was loaded on an Eloquent model already?

How to Force www or non-www in htaccess