Convert substr filter from character count to word count

Question

I'm using the getExcerpt() function below to dynamically set the length of a snippet of text. However, my substr method is currently based on character count. I'd like to convert it to word count. Do I need to separate function or is there a PHP method that I can use in place of substr?

function getExcerpt()
{
    //currently this is character count. Need to convert to word count
    $my_excerptLength = 100; 
    $my_postExcerpt = strip_tags(
        substr(
            'This is the post excerpt hard coded for demo purposes',
            0,
            $my_excerptLength 
            )
        );
    return ": <em>".$my_postExcerpt." [...]</em>";}
}

Answer 1

Use str_word_count

Depending on the parameters, it can either return the number of words in a string (default) or an array of the words found (in case you only want to use a subset of them).

So, to return the first 100 words of a snippet of text:

function getExcerpt($text)
{
    $words_in_text = str_word_count($text,1);
    $words_to_return = 100;
    $result = array_slice($words_in_text,0,$words_to_return);
    return '<em>'.implode(" ",$result).'</em>';
}