Get the number of words from the string or paragraph

Get Chunk/No of words from the string or paragraphs 
This is similar to substr of the built-in php function.

// Fetch the chunk of string by number of words from the paragraph or string.

function substr_words ($string, $num_words)
{
 $string = explode (' ', $string);
 $string = array_slice ($string, 0, $num_words);
 return implode (' ', $string);
}