在第四次换行后切掉一根弦

Question

我遇到了这个问题，我希望在第四次换行后切断一个长串并让它继续“......”

<?php
$teststring = "asddsadsadsadsaa\n
               asddsadsadsadsaa\n
               asddsadsadsadsaa\n
               asddsadsadsadsaa\n
               asddsadsadsadsaa\n
               asddsadsadsadsaa\n";
?>

应该成为：

<?php
$teststring = "asddsadsadsadsaa\n
               asddsadsadsadsaa\n
               asddsadsadsadsaa\n
               asddsadsadsadsaa...";
?>

我知道如何在第一个\n之后打破字符串，但我不知道在第四个之后怎么做。

我希望你能帮助我。

Answer 1

你可以爆炸字符串然后拿走你需要的所有部分

$newStr = ""; // initialise the string
$arr = explode("\n", $teststring);
if(count($arr) > 4) { // you've got more than 4 line breaks
   $arr = array_splice($arr, 0, 4); // reduce the lines to four
   foreach($arr as $line) { $newStr .= $line; } // store them all in a string
   $newStr .= "...";
} else {
   $newStr = $teststring; // there was less or equal to four rows so to us it'all ok
}

Answer 2

echo preg_replace ('~((.*?\x0A){4}).*~s', '\\1...', $teststring);

Answer 3

这样的东西？

$teststring = "asddsadsadsadsaa
               asddsadsadsadsaa
               asddsadsadsadsaa
               asddsadsadsadsaa
               asddsadsadsadsaa
               asddsadsadsadsaa";

$e = explode("\n", $teststring);

if (count($e) > 4)
{
    $finalstring = "";

    for ($i = 0; $i < 4; $i++)
    {
        $finalstring.= $e[$i];
    }
}
else
{
    $finalstring = $teststring;
}

echo "<pre>$finalstring</pre>";