How to Truncate a string in PHP to the word closest to a certain number of characters?

By using the wordwrap function. It splits the texts in multiple lines such that the maximum width is the one you specified, breaking at word boundaries. After splitting, you simply take the first line:

substr($string, 0, strpos(wordwrap($string, $your_desired_width), "\n"));

One thing this oneliner doesn't handle is the case when the text itself is shorter than the desired width. To handle this edge-case, one should do something like:

if (strlen($string) > $your_desired_width) 
{
    $string = wordwrap($string, $your_desired_width);
    $string = substr($string, 0, strpos($string, "\n"));
}

---

The above solution has the problem of prematurely cutting the text if it contains a newline before the actual cutpoint. Here a version which solves this problem:

function tokenTruncate($string, $your_desired_width) {
  $parts = preg_split('/([\s\n\r]+)/', $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));
}

Also, here is the PHPUnit testclass used to test the implementation:

class TokenTruncateTest extends PHPUnit_Framework_TestCase {
  public function testBasic() {
    $this->assertEquals("1 3 5 7 9 ",
      tokenTruncate("1 3 5 7 9 11 14", 10));
  }

  public function testEmptyString() {
    $this->assertEquals("",
      tokenTruncate("", 10));
  }

  public function testShortString() {
    $this->assertEquals("1 3",
      tokenTruncate("1 3", 10));
  }

  public function testStringTooLong() {
    $this->assertEquals("",
      tokenTruncate("toooooooooooolooooong", 10));
  }

  public function testContainingNewline() {
    $this->assertEquals("1 3\n5 7 9 ",
      tokenTruncate("1 3\n5 7 9 11 14", 10));
  }
}

EDIT :

Special UTF8 characters like 'à' are not handled. Add 'u' at the end of the REGEX to handle it:

$parts = preg_split('/([\s\n\r]+)/u', $string, null, PREG_SPLIT_DELIM_CAPTURE);

This will return the first 200 characters of words:

preg_replace('/\s+?(\S+)?$/', '', substr($string, 0, 201));

$WidgetText = substr($string, 0, strrpos(substr($string, 0, 200), ' '));

And there you have it — a reliable method of truncating any string to the nearest whole word, while staying under the maximum string length.

I've tried the other examples above and they did not produce the desired results.