Regex, PHP - finding words that need correction - php

Question

I have a long string with words. Some of the words have special letters.
For example a string "have now a rea$l problem with$ dolar inp$t"
and i have a special letter "$".
I need to find and return all the words with special letters in a quickest way possible.
What I did is a function that parse this string by space and then using “for” going over all the words and searching for special character in each word. When it finds it—it saves it in an array. But I have been told that using regexes I can have it with much better performance and I don’t know how to implement it using them.
What is the best approach for it?
I am a new to regex but I understand it can help me with this task?
My code: (forbiden is a const)
The code works for now, only for one forbidden char.
function findSpecialChar($x){
$special = "";
$exploded = explode(" ", $x);
foreach ($exploded as $word){
if (strpos($word,$forbidden) !== false)
$special .= $word;
}
return $special;
}

Answer 1

You could use preg_match like this:
// Set your special word here.
$special_word = "café";
// Set your sentence here.
$string = "I like to eat food at a café and then read a magazine.";
// Run it through 'preg_match''.
preg_match("/(?:\W|^)(\Q$special_word\E)(?:\W|$)/i", $string, $matches);
// Dump the results to see it working.
echo '<pre>';
print_r($matches);
echo '</pre>';
The output would be:
Array
(
[0] => café
[1] => café
)
Then if you wanted to replace that, you could do this using preg_replace:
// Set your special word here.
$special_word = "café";
// Set your special word here.
$special_word_replacement = " restaurant ";
// Set your sentence here.
$string = "I like to eat food at a café and then read a magazine.";
// Run it through 'preg_replace''.
$new_string = preg_replace("/(?:\W|^)(\Q$special_word\E)(?:\W|$)/i", $special_word_replacement, $string);
// Echo the results.
echo $new_string;
And the output for that would be:
I like to eat food at a restaurant and then read a magazine.
I am sure the regex could be refined to avoid having to add spaces before and after " restaurant " like I do in this example, but this is the basic concept I believe you are looking for.