I need a regex to match all single words and every pair of two words

Question

Im using PHP preg_match_all function and I need it to return an array of every single word AND every pair of words, including those single words, for example:

preg_match_all('/the regex/','Stackoverflow is awesome',$matches);

The $matches array should contain:

('Stackoverflow' , 'is' , 'awesome' , 'Stackoverflow is' , 'is awesome')

I've tried with this regex but not getting the expected results:

[a-z]+\s?[a-z]*

I think you don't look for a regex, this seems to be similar: http://stackoverflow.com/q/3200272/3933332 ? — Rizier123, Mar 16 '15 at 15:33

score 2 · Accepted Answer · answered Mar 16 '15 at 15:38

2

I don't think you can achieve that with just regular expressions. I would say, use explode and construct the array yourself.

$string = 'Stackoverflow is awesome';
$parts = explode(' ', $string);
for ($i = 1; $i < count($parts); $i++) {
    $parts[] = $parts[$i - 1] . ' ' . $parts[$i];
}

answered Mar 16 '15 at 15:38

Jeroen Noten

3,574
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1

I ended up using your answer, but instead of explode I use `preg_split("/[\s,.]+/", $string)` function because I am dealing with natural text (with commas, etc.) – Nicolas Durán Mar 16 '15 at 17:01

Avinash Raj · Answer 2 · 2015-03-16T16:32:44.993

Use \S+ to match all the words. And next you do \S+\s+\S+, it won't match the previously matched characters because regex by default won't do overlapping matches. In-order to make the regex engine to do overlapping matches, you need to put the pattern which matches two words at a time inside a capturing group and also place the capturing group inside positive lookarounds.

$s = "Stackoverflow is awesome";
$regex = '~(?=(\S+\s+\S+))|\S+~';
preg_match_all($regex, $s, $matches);
$matches = array_values(array_filter(call_user_func_array('array_merge', $matches)));
print_r($matches);

Output:

Array
(
    [0] => Stackoverflow
    [1] => is
    [2] => awesome
    [3] => Stackoverflow is
    [4] => is awesome
)

score 0 · Answer 3 · answered Mar 16 '15 at 15:50

This gives limits the phrasing to two words.

<?php
$str = "Stackoverflow is awesome";
$words = explode(" ",$str);
$num_words = count($words);
for ($i = 0; $i < $num_words; $i++) {
  for ($j = $i; $j < $num_words; $j++) {
    $num = 0;

    $temp = "";
    for ($k = $i; $k <= $j; $k++) { 
       $num++;
       $temp .= $words[$k] . " ";             
    }

    if($num < 3)
    echo $temp . "<br />";
  }
}
?>

Amit Verma · Answer 4 · 2015-03-16T16:06:44.947

0

Try this simple regex

 /\w+/i

Rewrite:

     preg_match_all('/\w+/i','Stackoverflow is awesome',$matches);
 print_r($matches);

See this in action here

edited Mar 16 '15 at 16:06

answered Mar 16 '15 at 16:00

Amit Verma

40,709
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score 0 · Answer 5 · answered Mar 16 '15 at 16:02

You can use lookaheads here:

preg_match_all('/(?=(\b(\w+)(?:\s+(\w+)\b|$)))/','Stackoverflow is awesome',$matches);

Now double words:

print_r($matches[1]);
Array
(
    [0] => Stackoverflow is
    [1] => is awesome
    [2] => awesome
)

And single words:

print_r($matches[2]);
Array
(
    [0] => Stackoverflow
    [1] => is
    [2] => awesome
)

PS: awesome prints in double words also because it is the last word.

I need a regex to match all single words and every pair of two words

5 Answers5