Adding span tags to post titles using regex

Question

My basic titles are something like

Part One: Part Two

And I'm trying to end up with something like this using the colon as what I find in the regex:

<span class="one-class">Part One:</span><br><span class="two-class">Part Two</span>

This is the original in entry-header.php and I want to continue to have that html:

if ( is_singular() ) {
            the_title( '<h1 class="entry-title">', '</h1>' );
        }
    

The following works as long as there is a colon in the title. If there is no colon, then none of the html gets added.

if ( is_singular() ) {
                        $string = get_the_title();
            $pattern = '~(.+): (.+)~i';
            $replacement = '<h1 class="entry-title"><span class="title-cite-pali">$1:</span><br><span class="title-english">$2</span></h1>';
            echo preg_replace($pattern, $replacement, $string);
        }
    

But I think what I really want is the following, but it doesn't work. The output is as if my added code is not there.

if ( is_singular() ) {
            $string = the_title( '<h1 class="entry-title test">', '</h1>' );
            $pattern = '~(.+): (.+)~i';
            $replacement = '<span class="title-cite-pali">$1:</span><br><span class="title-english">$2</span>';
            echo preg_replace($pattern, $replacement, $string);
            
        }
    

I think if I could get the above code working, it is preferable since if there was no colon at least the h1 tags would be added.

Answer 1

It's nice to use regex, but you can also achieve the same thing here by just splitting the string on ':' with explode e.g.:

    $matches = explode(":", get_the_title()) ;

    if (count($matches) == 2) {
       $result = "foo bar $matches[0] foo bar $matches[1]";
    } else {
       // case with no : in title
       $result = "foo bar $matches[0] foo bar";
    }
    echo $result;

Answer 2

You don't need a regex.

First, grab the title as a string variable:

$title = get_the_title();

Then, find the location of the first colon:

$colon = strpos( $title, ':' );

If there is no colon, handle that:

if ( $colon === FALSE ) {
    // there was no colon, handle that!
    echo '<h2>' . esc_html( $title ) . '</h2>';
} else {
    // the rest of the code
}

What about the rest of the code that goes in the else? Well, lets split it in two:

$first_part = substr( $title, 0, $colon );
$second_part = substr( $title, $colon + 1, strlen( $title ) );

Now we can output them differently:

echo '<span>' . $first_part . '</span>';
echo '<span>' . $second_part . '</span>';