使用regex php匹配文件中的单词

Question

I'm new with regex and php. I know this quite simple but i just can't get it. Now, i have file words.txt that contain:

happy
sad
laugh

I want to find match this sentence with my words.txt:

I am happy

So far, i've tried this but it doesn't valid because it read as a sentence not words: (not yet implement regex bcs im confused)

$input0= "I am happy";
$handle = fopen('words.txt', 'r');
$valid = false; 
while (($buffer = fgets($handle)) !== false) {
if (strpos($buffer, $input0) !== false) { // here's the problem
    $valid = TRUE;
    break;
   }      
}
if($valid == TRUE){
//print the matches word
}
fclose($handle);

can u help me? :(

Answer 1

Depending on your final goal you may not even need regexp here, since you want to match entire word with no variable part.

if you want to have a loop on your keywords a simple str_replace() would do the job to replace the word by an emphasize one for instance, or simple if (strpos($input0, $word) !== false) to just check if found in sentence and find position.

But if you want to avoid a loop, for faster results and especially if you have many words preg_match_all() will do what you need as said by Zanderwar. Here is an example:

$input0= "I am happy but sometimes quite pretty sad. It depends but I prefer to be happy in general.\nMy paragraph also continue on multilines\nend it makes me laugh and rejoy. I am so happy. HAPPY?";
// $contents = file_get_contents('words.txt');
$contents = "happy\nsad\nlaugh";

$words_list = str_replace("\n", '|', $contents);

if (preg_match_all("~($words_list)~si", $input0, $matches))
{
    print_r(array($matches));
    // Do what you want
}

The i flag match case insensitive if you need.

The s flag match on multilines content.

[EDIT] to add more details on regexp

In the pattern you need a delimiter which can be ~ because it is very seldom used in sentences and strings to match so you wont need to escape / as when you use / delimiter.

also I am joining your words like ~(sad|joy|happy)~ if you want to capture the words. if you don't you need a group like (?:sad|joy|happy)

the | means or.

You can try to replace regex ~($words_list)~si by ~(?:$words_list)~si if you dont need capturing - and you don't - you will then have only one level of captures in $matches array, at position [0] it is always the full match. but here you don't have more complex patterns to match and so no need to capture