从文件读取第一行的最快方法 [英] Quickest Way to Read First Line from File

问题描述

仅从文件中读取第一行的最快，最简单的方法是什么?我知道您可以使用file，但就我而言，浪费时间加载整个文件毫无意义.

What's the quickest, easiest way to read the first line only from a file? I know you can use file, but in my case there's no point in wasting the time loading the whole file.

最好是单线的.

推荐答案

好吧，你可以这样做:

$f = fopen($file, 'r');
$line = fgets($f);
fclose($f);

这不是一行，但是如果您将其设置为一行，则可能会被错误地检查错误，或者使资源的开放时间超出了您的需要，所以我会说保持多行

It's not one line, but if you made it one line you'd either be screwed for error checking, or be leaving resources open longer than you need them, so I'd say keep the multiple lines

如果您绝对知道文件存在，则可以使用单线:

If you ABSOLUTELY know the file exists, you can use a one-liner:

$line = fgets(fopen($file, 'r'));

原因是PHP为资源实现了 RAII .

The reason is that PHP implements RAII for resources.

这意味着当文件句柄超出范围时(在这种情况下，在调用fgets之后立即发生)，它将关闭.

That means that when the file handle goes out of scope (which happens immediately after the call to fgets in this case), it will be closed.

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