How to convert HTML "class" attribute to css selector using php language?

Question

How to convert a string with class into a selector even if it contains many spaces between classes?

Input data:

$html_classes = 'class1    class2  class3 ';

Necessary result:

.class1.class2.class3

This example is not appropriate as there may be many spaces between classes

$result = '.' . str_replace( ' ', '.', $html_classes )

Answer 1

Just replace all extra spaces to singles first. And run trim() to remove spaces on the beginning and at the end.

$html_classes = 'class1    class2  class3 ';
$html_classes = trim(preg_replace('/\s+/',' ',$html_classes));
$result = '.' . str_replace(' ','.',$html_classes);

Answer 2

Try this:

<?php
$html_classes = 'class1    class2  class3 ';
$parts = explode(" ", $html_classes);
$results = "";
foreach($parts as $c){
    if($c != ""){
        $results .= "." . $c;
    }
}
echo $results;
?>

The results I got:

.class1.class2.class3

Hope that helps.