php – file_put_contents上的互斥标志？

发布时间：2020-12-13 21:35:05 所属栏目：PHP教程来源：网络整理

导读：在 file_put_contents()文档中,它说明如下： FILE_APPEND： Mutually exclusive with LOCK_EX since appends are atomic and thus there is no reason to lock. LOCK_EX： Mutually exclusive with FILE_APPEND. 然而,下面的几行代码我看到以下代码： ?php$f

在 file_put_contents()文档中,它说明如下：

FILE_APPEND：

Mutually exclusive with LOCK_EX since
appends are atomic and thus there is
no reason to lock.

LOCK_EX：

Mutually exclusive with FILE_APPEND.

然而,下面的几行代码我看到以下代码：

<?php
$file = 'people.txt';
// The new person to add to the file
$person = "John Smithn";
// Write the contents to the file,// using the FILE_APPEND flag to append the content to the end of the file
// and the LOCK_EX flag to prevent anyone else writing to the file at the same time
file_put_contents($file,$person,FILE_APPEND | LOCK_EX);
?>

那么,FILE_APPEND和LOCK_EX标志是否相互排斥？如果是,为什么他们在示例中使用它？这是一个糟糕的文件案例吗？

感谢您的输入！

解决方法

那只是糟糕的文档. manual clearly states：

FILE_APPEND : If file filename
already exists,append the data to the
file instead of overwriting it.
Mutually exclusive with LOCK_EX since
appends are atomic and thus there is
no reason to lock.

LOCK_EX : Acquire an exclusive lock
on the file while proceeding to the
writing. Mutually exclusive with
FILE_APPEND.

你说的例子是：

<?php
$file = 'people.txt';
// The new person to add to the file
$person = "John Smithn";
// Write the contents to the file,FILE_APPEND | LOCK_EX);
?>

看起来编写这个例子的人误解了“互相排斥”的含义,或者产生了一些秘密的,无证件的行为.

（编辑：李大同）

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