php不破坏单词截取子字符串

/* 
    snippet(phrase,[max length],[phrase tail])
    snippetgreedy(phrase,[max length before next space],[phrase tail])
  
*/
  
function snippet($text,$length=64,$tail="...") {
    $text = trim($text);
    $txtl = strlen($text);
    if($txtl > $length) {
        for($i=1;$text[$length-$i]!=" ";$i++) {
            if($i == $length) {
                return substr($text,0,$length) . $tail;
            }
        }
        $text = substr($text,0,$length-$i+1) . $tail;
    }
    return $text;
}
  
// It behaves greedy, gets length characters ore goes for more
  
function snippetgreedy($text,$length=64,$tail="...") {
    $text = trim($text);
    if(strlen($text) > $length) {
        for($i=0;$text[$length+$i]!=" ";$i++) {
            if(!$text[$length+$i]) {
                return $text;
            }
        }
        $text = substr($text,0,$length+$i) . $tail;
    }
    return $text;
}
  
// The same as the snippet but removing latest low punctuation chars,
// if they exist (dots and commas). It performs a later suffixal trim of spaces
  
function snippetwop($text,$length=64,$tail="...") {
    $text = trim($text);
    $txtl = strlen($text);
    if($txtl > $length) {
        for($i=1;$text[$length-$i]!=" ";$i++) {
            if($i == $length) {
                return substr($text,0,$length) . $tail;
            }
        }
        for(;$text[$length-$i]=="," || $text[$length-$i]=="." || $text[$length-$i]==" ";$i++) {;}
        $text = substr($text,0,$length-$i+1) . $tail;
    }
    return $text;
}
  
/*
echo(snippet("this is not too long to run on the column on the left, perhaps, or perhaps yes, no idea") . "<br>");
echo(snippetwop("this is not too long to run on the column on the left, perhaps, or perhaps yes, no idea") . "<br>");
echo(snippetgreedy("this is not too long to run on the column on the left, perhaps, or perhaps yes, no idea"));
*/