如何在不破坏单词结构的前提下，将PHP代码截取为长尾词？

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php

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")); */