PHP preg_match using RegEx to match a word

Question

I want to find all the demo words using PHP and regEx.

$input ='demo';
$pattern = ''; //$input can be used along with regex, please help here 
$text = 'This is dem*#o text, contains de12mo3 text, is .demo23* text' 

if(preg_match($pattern, $text))
{
 echo 'found';
}else{
 echo'not found';
}

the search word demo in the text may be present in the following format

1) may start with special characters/numbers Eg. "12*demo"
2) may contain special characters/numbers within the word Eg.  "de12*mo"
3) may end with special characters/numbers Eg. "demo12*"

please help I am stuck, thanks in advance!

Note: The $input can be max. of 15 in length

@PhpMyCoder I am new to RegEx, this is what I am trying /[\W$demo\W]/ ,but problem is, it is not able to detect special characters present within word Eg. de123*# — pcdhan
– pcdhan, Commented Jun 24, 2012 at 7:23
@pcdhan Good that you tried something, make sure to put it in the question next time. — John V.
– John V., Commented Jun 24, 2012 at 7:30

Bailey Parker · Accepted Answer · 2012-06-24 07:47:03Z

3

The Solution

I would start by removing all special characters and numbers from the string, and then matching the word using word boundaries:

$cleaned = preg_replace('/[^a-z ]+/i', '', 'This is dem*#o text, contains de12mo3 text, is .demo23* text');

preg_match_all('/\bdemo\b/i', $cleaned, $matches, PREG_OFFSET_CAPTURE);

var_dump($matches);

Will give you (Codepad Demo):

array(1) {
  [0] => array(3) {
    [0] => array(2) {
      [0] => string(4) "demo"
      [1] => int(8)
    }

    [1] => array(2) {
      [0] => string(4) "demo"
      [1] => int(27)
    }

    [2] => array(2) {
      [0] => string(4) "demo"
      [1] => int(40)
    }
  }
}

Explanation

The first line replaces any characters in your string (called the subject argument) that match /[a-z ]+/i with '', essentially removing the characters. The regex matches any character (or group of characters) that is not (^) the letters a-z or a space. The i flag tells regex that the search should be case insensitive (This saves us from writing a-zA-Z).

The next line uses word boundaries to match the word 'demo'. However, you could substitute in any word.

New Regex Techniques

edited Jun 24, 2012 at 7:47

answered Jun 24, 2012 at 7:27

Bailey Parker

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3 Comments

Bailey Parker Over a year ago

@pcdhan Let us know if you need any help with the implementation.

pcdhan Over a year ago

successfully implemented, again thanks a lot, it really helped me.

Bailey Parker Over a year ago

@pcdhan Any time. If this answered your question you should mark it as solved by clicking the checkmark next to it.

flec · Accepted Answer · 2012-06-24 07:27:53Z

1

/\b[^a-z]*d[^a-z]*e[^a-z]*m[^a-z]*o[^a-z]*\b/i

Matches anything but a-z between the demo characters

answered Jun 24, 2012 at 7:27

flec

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2 Comments

pcdhan Over a year ago

thanks @flec, the $input can be max. of 15 chars in length.

flec Over a year ago

Use strlen() to check the lenght afterwards

Menztrual · Accepted Answer · 2012-06-24 07:24:50Z

0

Probably not efficient; But you could use this:

/(.*)d(.*)e(.*)m(.*)o(.*)/i

That would match anything.

answered Jun 24, 2012 at 7:24

Menztrual

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