CODEWITHSUNDEEP
phpregex
user995789
user995789

Reputation: 279

php regex how to remove duplicate strings

here is a long string like"abc,adbc,abcf,abc,adbc,abcf"

I want to use regex to remove the duplicate strings which are seperated by comma

the following is my codes, but the result is not what I expect.

$a='abc,adbc,abcf,abc,adbc,abcf';
$b=preg_replace('/(,[^,]+,)(?=.*?\1)/',',',','.$a.',');
echo $b;

output:,adbc,abc,adbc,abcf,

It should be : ,abc,adbc,abcf,

please point my problem. thanks.

Upvotes: 2

Views: 1552

Answers (4)

Suresh Kamrushi
Suresh Kamrushi

Reputation: 16086

Here I am sharing simple php logic instead regex

$a='abc,adbc,abcf,abc,adbc,abcf';

$pieces = explode(",", $a);
$unique_values = array_unique($pieces);
$string = implode(",", $unique_values);

Upvotes: 3

Tapas Pal
Tapas Pal

Reputation: 7207

Try this....

$string='abc,adbc,abcf,abc,adbc,abcf';
$exp = explode(",", $string);
$arr = array_unique($exp);
$output=implode(',', $arr);

Upvotes: 0

MatRt
MatRt

Reputation: 3534

You can also try

echo implode(",", array_unique(preg_split(",", $yourLongString)));

Upvotes: 0

Raj Adroit
Raj Adroit

Reputation: 3878

Here is positive lookahead base attempt on regex based solution to OP's problem.

$arr = array('ball ball code', 'abcabc bde bde', 'awycodeawy');
foreach($arr as $str)
   echo "'$str' => '" . preg_replace('/(\w{2,})(?=.*?\\1)\W*/', '', $str) ."'\n";

OUTPUT

'ball ball code' => 'ball code'
'abcabc bde bde' => 'abc bde'
'awycodeawy' => 'codeawy'

As you can for the input 'awycodeawy' it makes it to 'codeawy' instead of 'awycode'. The reason is that it is possible to find a variable length lookahead something which is not possible for lookbehind.

Upvotes: 0

Related Questions