Question

这应该是相当简单的。说我有以下代码：

$output = file_get_contents($random_name . ".txt");
echo "<pre>";
echo str_replace("\n", "\nN ", $output);
echo "</pre>";

$output看起来像这样：

PDF Test File
N Congratulations, your computer is equipped with a PDF (Portable Document Format)
N reader! You should be able to view any of the PDF documents and forms available on
N our site. PDF forms are indicated by these icons:
N or.
N 
N

让我们说我想通过以下方式摆脱这两个最后的换行符：

$outputTrimmed = trim($output, "\n");

我认为，那会输出：

PDF Test File
N Congratulations, your computer is equipped with a PDF (Portable Document Format)
N reader! You should be able to view any of the PDF documents and forms available on
N our site. PDF forms are indicated by these icons:
N or.

但相反，这段代码：

$output = file_get_contents($random_name . ".txt");
$outputTrimmed = trim($output, "\n");
echo "<pre>";
echo str_replace("\n", "\nN ", $outputTrimmed);
echo "</pre>";

结果：

PDF Test File
N Congratulations, your computer is equipped with a PDF (Portable Document Format)
N reader! You should be able to view any of the PDF documents and forms available on
N our site. PDF forms are indicated by these icons:
N or.
N 
N

我做错了什么？它可能是真的，真的简单...所以我道歉。

Answer 1

您可能正在使用Windows End-of-line样式。

哪个是\r\n，而不仅仅是\n。

尝试更换两者。

或者，不要指定任何charlist（第二个参数）。指定\n即表示仅修剪\n

trim($output)

请参阅此处的文档：http://www.w3schools.com/php/func_string_trim.asp#gsc.tab=0

编辑（来自您的评论）：

如果trim（）不起作用，请尝试将字符串更改为字节数组并检查完全字符串末尾的字符。这让我怀疑还有其他一些不可打印的角色在干扰。

$byteArray = unpack('C*', $output);
var_dump($byteArray);

http://www.asciitable.com/

Answer 2

试试这个

   $output1 = file_get_contents($random_name . ".txt");
   $output=str_replace("\n", "\nN ", $output1);
   $outputTrimmed = trim($output,"\n");
   echo "<pre>";
   echo $outputTrimmed;
   echo "<pre>";

输出

  PDF Test File
  N  Congratulations, your computer is equipped with a PDF (Portable Document Format)
  N  reader! You should be able to view any of the PDF documents and forms available on    
  N  our site. PDF forms are indicated by these icons:
  N or .

修剪不删除结束换行符？

2 个答案: