blocks|key|1220272|text|请改用sha1_file()。如果您只需要查看文件是否不同，它会更快，而且工作得很好。如果文件很大，则将整个字符串相互比较可能会非常繁重。由于sha1_file()返回40个字符的文件表示形式，因此比较文件将非常快。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1220273|您还可以考虑其他方法，如比较filemtime或文件大小，但这将为您提供保证的结果，即使只有一位发生了变化。|1220274|entityMap|0|LINK|mutability|MUTABLE|url|http://fi2.php.net/sha1_file^0|3|B|1Z|B|3|B|0|0|E|9|0^^$0|@$1|2|3|4|5|6|7|P|8|@$9|Q|A|R|B|C]|$9|S|A|T|B|C]]|D|@$9|U|A|V|1|W]]|E|$]]|$1|F|3|G|5|6|7|X|8|@$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|10|8|@]|D|@]|E|$]]]|I|$J|$5|K|L|M|E|$N|O]]]]

Use <a href="http://fi2.php.net/sha1_file" rel="noreferrer"><code>sha1_file()</code></a> instead. It's faster and works fine if you just need to see whether the files differ. If the files are large, comparing the whole strings to each other can be very heavy. As <code>sha1_file()</code> returns an 40 character representation of the file, comparing files will be very fast.

You can also consider other methods like comparing <code>filemtime</code> or filesize, but this will give you guaranteed results even if there's just one bit that's changed.

blocks|key|1006025|text|看起来有点重。这会将两个文件完全作为字符串加载，然后进行比较。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1006026|我认为您最好手动打开这两个文件，然后逐个检查它们，也许只需先检查一下文件大小。|1006027|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

Seems a bit heavy. This will load both files completely as strings and then compare.

I think you might be better off opening both files manually and ticking through them, perhaps just doing a filesize check first.

blocks|key|1006071|text|你在这里做的事情没有任何问题，承认它有点低效。获取每个文件的内容并进行比较，特别是对于较大的文件或二进制数据，您可能会遇到问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1006072|我会看一下filetime+(最后一次修改)和filesize，并运行一些测试，看看它是否适用于您。它应该是你所需要的计算能力的一小部分。|offset|length|1006073|entityMap|0|LINK|mutability|MUTABLE|url|http://php.net/manual/en/function.filemtime.php|1|http://php.net/manual/en/function.filesize.php^0|0|5|8|0|N|8|1|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Q|8|@]|9|@$D|R|E|S|1|T]|$D|U|E|V|1|W]]|A|$]]|$1|F|3|-4|5|6|7|X|8|@]|9|@]|A|$]]]|G|$H|$5|I|J|K|A|$L|M]]|N|$5|I|J|K|A|$L|O]]]]

There isn't anything wrong with what you are doing here, accept it is a little inefficient. Getting the contents of each file and comparing them, especially with larger files or binary data, you may run into problems.

I would take a look at <a href="http://php.net/manual/en/function.filemtime.php" rel="nofollow noreferrer">filetime</a> (last modified) and <a href="http://php.net/manual/en/function.filesize.php" rel="nofollow noreferrer">filesize</a>, and run some tests to see if that works for you. It should be all you need at a fraction of the computation power.

blocks|key|1006133|text|这是可行的，但比起计算两个文件的校验和并比较它们，效率要低得多。校验和算法的理想候选者是SHA1和MD5。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1006134|http://php.net/sha1_file|offset|length|1006135|http://php.net/md5_file|1006136|if+(sha1_file($source)+==+sha1_file($dest))+{
++++/*+...+*/
}|code-block|syntax|javascript|1006137|entityMap|0|LINK|mutability|MUTABLE|url|1^0|0|0|O|0|0|0|N|1|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@]|9|@$D|W|E|X|1|Y]]|A|$]]|$1|F|3|G|5|6|7|Z|8|@]|9|@$D|10|E|11|1|12]]|A|$]]|$1|H|3|I|5|J|7|13|8|@]|9|@]|A|$K|L]]|$1|M|3|-4|5|6|7|14|8|@]|9|@]|A|$]]]|N|$O|$5|P|Q|R|A|$S|C]]|T|$5|P|Q|R|A|$S|G]]]]

Ths will work, but is inherently more inefficient than calculating checksum for both files and comparing these. Good candidates for checksum algorithms are SHA1 and MD5.

<a href="http://php.net/sha1_file" rel="nofollow noreferrer">http://php.net/sha1_file</a>

<a href="http://php.net/md5_file" rel="nofollow noreferrer">http://php.net/md5_file</a>

<pre><code>if (sha1_file($source) == sha1_file($dest)) {
 /* ... */
}
</code></pre>

blocks|key|1220465|text|我注意到有一件事是缺少N！因素。换句话说，要执行filesize()函数，首先必须检查每个文件和所有其他文件。为什么？如果第一个文件和第二个文件的大小不同，但第三个文件的大小相同，该怎么办？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1220466|所以首先-如果你想做filesize类型的事情，你需要得到你将要处理的所有文件的列表-然后使用完整的/字符串作为数组的键，然后存储filesize()信息。然后对数组进行排序，这样所有大小相同的文件都排成一排。然后，您可以检查文件大小。然而，这并不意味着它们真的是相同的-只是它们的大小相同。|1220467|您需要执行类似于sha1_file()命令的操作，并且像上面一样，创建一个数组，其中键是键，名称是键，值是返回值。对它们进行排序，然后简单地遍历存储要测试的sha1_file()值的数组。那么A==B呢？是。执行任何其他测试，然后删除第二个文件并继续。|1220468|我为什么要评论呢？我正在处理同样的问题，我刚刚发现我的程序不能正常工作。因此，现在我将使用sha1_file()函数对其进行更正。:-)|1220469|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|L|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|M|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

Something I noticed is there is a lack of the N! factor. In other words - to do the filesize() function you would first have to check every file against all of the other files. Why? What if the first file and the second file are different sizes but the third file is the same size.
So first - you need to get a list of all of the files you are going to work with If you want to do the filesize type of thing - then use the COMPLETE / string as the key for an array and then store the filesize() information. Then you sort the array so all files which are the same size are lined up. THEN you can check file sizes. However - this does not mean they really are the same - only that they are the same size.
You need to do something like the sha1_file() command and, like above, make an array where the keys are the / names are the keys and the values is the value returned. Sort those, and then just do a simple walk through the array storing the sha1_file() value to test against. So is A==B? Yes. Do any additional tests, then get rid of the SECOND file and continue.
Why am I commenting? I'm working on this same problem and I just found out my program did not work correctly. So now I'm going to go correct it using the sha1_file() function. :-)

I want to synchronize two directories. And I use 

<pre><code>file_get_contents($source) === file_get_contents($dest)
</code></pre>

to compare two files. Is there any problem to do this?

Can I use file_get_contents() to compare two files?

我想同步两个目录。我使用了file_get_contents($source) === file_get_contents($dest)来比较两个文件。这样做有什么问题吗？

问我可以使用file_get_contents()来比较两个文件吗？
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问我可以使用file_get_contents()来比较两个文件吗？
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