How to truncate a string in PHP to the sentence closest to a certain number of characters?

I want to truncate/shorten my string to the sentence closest to a ceratain number of characters.

I have a working function, but my function truncate to the word closest to a certaion number of characters instead.

function shortenString($string, $your_desired_width) {
  $parts = preg_split('/([snr]+)/', $string, null, PREG_SPLIT_DELIM_CAPTURE);
  $parts_count = count($parts);

  $length = 0;
  $last_part = 0;
  for (; $last_part < $parts_count; ++$last_part) {
    $length += strlen($parts[$last_part]);
    if ($length > $your_desired_width) { break; }
  }

  return implode(array_slice($parts, 0, $last_part));
}

For example:

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer malesuada eleifend orci, eget dignissim ligula porttitor cursus. Praesent in blandit enim. Maecenas vitae eleifend est. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Maecenas pulvinar gravida tempor.

Should be shortened to:

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer malesuada eleifend orci, eget dignissim ligula porttitor cursus.

Instead of breaking the sentence like this:

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer malesuada eleifend orci, eget dignissim ligula porttitor cursus. Praesent in

Help is appreciated.

Answer

This is what I came up with… you should check if the sentence is longer than the len you are looking for.. among other things like what g13n said. It might be better if the sentence is too short/long to chopping it off and putting “…”. Plus, you would have to check/convert whitespace since strrpos will only look for what is given.

$maxlen = 150;
$file = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer malesuada eleifend orci, eget dignissim ligula porttitor cursus. Praesent in blandit enim. Maecenas vitae eleifend est. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Maecenas pulvinar gravida tempor.";
if ( strlen($file) > $maxlen ){
    $file = substr($file,0,strrpos($file,". ",$maxlen-strlen($file))+1);
}

if you want to use the same function you have, you can try this:

function shortenString($string, $your_desired_width) {
  $parts = preg_split('/([snr]+)/', $string, null, PREG_SPLIT_DELIM_CAPTURE);
  $parts_count = count($parts);

  $length = 0;
  $last_part = 0;
  $last_taken = 0;
  foreach($parts as $part){
    $length += strlen($part);
    if ( $length > $your_desired_width ){
        break;
    }
    ++$last_part;
    if ( $part[strlen($part)-1] == '.' ){
        $last_taken = $last_part;
    }
  }
  return implode(array_slice($parts, 0, $last_taken));
}