Search for repeated consecutive characters in strings and replace each string with 1 or 0

Question

I am having an array

$array = array("ab","aab","abb","abab","abaab","abbb");

I want to search the elements that contain duplicate consecutive characters like aab, abb, abbb and replace them with 1.

Conversely, if an element does not contain any duplicate consecutive characters, (like ab and abab) then it should be replaced with 0.

Scuzzy · Answer 1 · 2017-11-11T09:30:01.460

1

This approach uses array_map and preg_match to return an array of true/false matches based on a repeating string. The keys will match your input array.

(.) finds any character and puts it into the first capturing group, then \1 makes sure the exact matching character follows it.

$array = array("ab","aab","abb","abab","abaab","abbb");
function StringHasRepetition( $string )
{
  return preg_match('/(.)\1/', $string);
}
$matches = array_map('StringHasRepetition',$array);
print_r( $matches );
// Array ( [0] => 0 [1] => 1 [2] => 1 [3] => 0 [4] => 1 [5] => 1 )

As a Lambda function:

$array = array("ab","aab","abb","abab","abaab","abbb");
$matches = array_map( function( $string ){
  return preg_match('/(.)\1/', $string);
} ,$array);
print_r( $matches );
// Array ( [0] => 0 [1] => 1 [2] => 1 [3] => 0 [4] => 1 [5] => 1 )

edited Nov 11 '17 at 09:30

answered Nov 11 '17 at 09:11

Scuzzy

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I misunderstood the question at first. Great answer +1. Perfect regex pattern. Tight. – mickmackusa Nov 11 '17 at 10:47
Thanks, sometimes regex is the solution! :D – Scuzzy Nov 11 '17 at 10:55
I just realized a cleaner way. See my answer. (I still like yours, so I am not removing the upvote.) – mickmackusa Nov 11 '17 at 11:00

mickmackusa · Answer 2 · 2017-11-19T07:20:49.483

preg_replace() can manipulate your entire array with just two regex patterns in a single call. First convert strings with no consecutive repeated characters to 0. Then convert all non 0 values to 1.

Code: (See Demo Link for a more verbose breakdown of the method)

$array=["ab","aab","abb","abab","abaab","abbb",'1','11','10','0','00100','1101','01'];
var_export(preg_replace(['/^(?:(.)(?!\1))*$/','/^(?!0$).*/'],[0,1],$array));

Output:

array (
  0 => '0',
  1 => '1',
  2 => '1',
  3 => '0',
  4 => '1',
  5 => '1',
  6 => '0',
  7 => '1',
  8 => '0',
  9 => '0',
  10 => '1',
  11 => '1',
  12 => '0',
)

Search for repeated consecutive characters in strings and replace each string with 1 or 0

2 Answers2