blocks|key|347581|text|所有这些都可以使用。三者之间有细微的区别：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|347582|与gzip命令行工具相同，|offset|length|style|CODE|347583|使用GZIP文件格式。此文件格式具有包含可选元数据的标题、压缩数据，以及包含ZLIB校验和和check.|unordered-list-item|347584|使用CRC32格式的长度的页脚。它的页眉较短，仅用于标识压缩格式和压缩数据，包含checksum.|347585|的页脚单独使用原始DEFLATE算法，这是其他两种格式的基础。|347586|347587|这三种算法在幕后都使用相同的算法，因此它们在速度或效率上不会有区别。gzencode()增加了包含原始文件名和其他环境数据的功能(当您只是压缩字符串时，不会使用此功能)。gzencode()和gzcompress()都添加了校验和，因此可以验证归档的完整性，这对于不可靠的传输和存储方法很有用。如果所有内容都存储在本地，并且不需要任何额外的元数据，那么gzdeflate()就足够了。对于可移植性，我推荐使用gzencode()+(GZIP格式)，在其他工具中，它可能比gzcompress()+(ZLIB格式)支持得更好。|347588|当压缩非常短的字符串时，每个方法的开销变得相关，因为对于非常短的输入，开销可能包括输出的很大一部分。每种方法的开销(通过压缩空字符串来测量)为：|347589|347590|gzencode('')+=+20+bytes|347591|gzcompress('')+=8+bytes|347592|gzdeflate('')+=2字节|347593|347594|entityMap^0|0|1|4|0|0|0|0|0|Y|A|2D|A|2O|C|4W|B|5O|A|6J|C|0|0|0|0|C|0|0|E|0|0|D|0|0^^$0|@$1|2|3|4|5|6|7|13|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|14|8|@$D|15|E|16|F|G]]|9|@]|A|$]]|$1|H|3|I|5|J|7|17|8|@]|9|@]|A|$]]|$1|K|3|L|5|J|7|18|8|@]|9|@]|A|$]]|$1|M|3|N|5|J|7|19|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|1A|8|@]|9|@]|A|$]]|$1|P|3|Q|5|6|7|1B|8|@$D|1C|E|1D|F|G]|$D|1E|E|1F|F|G]|$D|1G|E|1H|F|G]|$D|1I|E|1J|F|G]|$D|1K|E|1L|F|G]|$D|1M|E|1N|F|G]]|9|@]|A|$]]|$1|R|3|S|5|6|7|1O|8|@]|9|@]|A|$]]|$1|T|3|-4|5|6|7|1P|8|@]|9|@]|A|$]]|$1|U|3|V|5|J|7|1Q|8|@$D|1R|E|1S|F|G]]|9|@]|A|$]]|$1|W|3|X|5|J|7|1T|8|@$D|1U|E|1V|F|G]]|9|@]|A|$]]|$1|Y|3|Z|5|J|7|1W|8|@$D|1X|E|1Y|F|G]]|9|@]|A|$]]|$1|10|3|-4|5|6|7|1Z|8|@]|9|@]|A|$]]|$1|11|3|-4|5|6|7|20|8|@]|9|@]|A|$]]]|12|$]]

All of these can be used. There are subtle differences between the three:

<ul>
<li><a href="http://php.net/manual/en/function.gzencode.php" rel="noreferrer">gzencode()</a> uses the GZIP file format, the same as the <code>gzip</code> command line tool. This file format has a header containing optional metadata, DEFLATE compressed data, and footer containing a CRC32 checksum and length check.</li>
<li><a href="http://php.net/manual/en/function.gzcompress.php" rel="noreferrer">gzcompress()</a> uses the ZLIB format. It has a shorter header serving only to identify the compression format, DEFLATE compressed data, and a footer containing an ADLER32 checksum.</li>
<li><a href="http://php.net/manual/en/function.gzdeflate.php" rel="noreferrer">gzdeflate()</a> uses the raw DEFLATE algorithm on its own, which is the basis for both of the other formats.</li>
</ul>

All three use the same algorithm under the hood, so they won't differ in speed or efficiency. <code>gzencode()</code> adds the ability to include the original file name and other environmental data (this is unused when you are just compressing a string). <code>gzencode()</code> and <code>gzcompress()</code> both add a checksum, so the integrity of the archive can be verified, which can be useful over unreliable transmission and storage methods. If everything is stored locally and you don't need any additional metadata then <code>gzdeflate()</code> would suffice. For portability I'd recommend <code>gzencode()</code> (GZIP format) which is probably better supported than <code>gzcompress()</code> (ZLIB format) among other tools.

When compressing very short strings the overhead of each method becomes relevant since for very short input the overhead can comprise a significant part of the output. The overhead for each method, measured by compressing an empty string, is:

<ul>
<li><code>gzencode('')</code> = 20 bytes</li>
<li><code>gzcompress('')</code> = 8 bytes</li>
<li><code>gzdeflate('')</code> = 2 bytes</li>
</ul>

blocks|key|3337992|text|所有的方法本质上都是一样的，它们之间的区别主要是在头部。就我个人而言，我会使用gzencode，这将产生相当于对gzip实用程序的命令行调用的输出。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3337993|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

All methods are essentially the same, the difference between them is mostly in the headers. personally I'd use gzencode, this will produce output which is equal to a commandline invocation to the gzip utility.

blocks|key|3338001|text|我不是PHP专家，无法回答提出的问题，但似乎这里有很多猜测，并提供了模糊的信息。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3338002|DEFLATE是ZLIB、GZIP等使用的压缩算法的名称。理论上，GZIP支持可选的压缩算法，但在实践中，根本没有。|3338003|没有“GZIP算法”这回事。GZIP使用DEFLATE算法，并在压缩数据周围放置成帧数据。使用GZIP，您可以添加诸如文件名、文件时间、CRC，甚至注释之类的内容。不过，这个元数据是可选的，许多gzippers都忽略了它。|3338004|ZLIB是相似的，除了具有不同的、更有限的元数据集和特定的2字节头。|3338005|这都是在IETF+RFC+1950、1951和1952中实现的。|offset|length|3338006|说“gzip算法压缩得比DEFLATE好”完全是无稽之谈。没有gzip算法。GZIP格式的中使用的算法是DEFLATE。|style|BOLD|3338007|entityMap|0|LINK|mutability|MUTABLE|url|http://www.ietf.org/rfc/rfc1950.txt|1|http://www.ietf.org/rfc/rfc1951.txt|2|http://www.ietf.org/rfc/rfc1952.txt^0|0|0|0|0|D|4|0|I|4|1|N|4|2|0|19|E|0^^$0|@$1|2|3|4|5|6|7|11|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|12|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|13|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|14|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|15|8|@]|9|@$J|16|K|17|1|18]|$J|19|K|1A|1|1B]|$J|1C|K|1D|1|1E]]|A|$]]|$1|L|3|M|5|6|7|1F|8|@$J|1G|K|1H|N|O]]|9|@]|A|$]]|$1|P|3|-4|5|6|7|1I|8|@]|9|@]|A|$]]]|Q|$R|$5|S|T|U|A|$V|W]]|X|$5|S|T|U|A|$V|Y]]|Z|$5|S|T|U|A|$V|10]]]]

I am no PHP expert and cannot answer the question posed, but it seems like there is a lot of guessing going on here, and fuzzy information being proffered. 

DEFLATE is the name of the compression algorithm that is used by ZLIB, GZIP and others. In theory, GZIP supports alternative compression algorithms, but in practice, there are none. 

There is no such thing as "the GZIP algorithm". GZIP uses the DEFLATE algorithm, and puts framing data around the compressed data. With GZIP you can add things like the filename, the time of the file, a CRC, even a comment. This metadata is optional, though, and many gzippers just omit it. 

ZLIB is similar, except with a different, more limited set of metadata, and a specific 2-byte header. 

This is all in IETF RFCs <a href="http://www.ietf.org/rfc/rfc1950.txt" rel="noreferrer">1950</a>, <a href="http://www.ietf.org/rfc/rfc1951.txt" rel="noreferrer">1951</a>, and <a href="http://www.ietf.org/rfc/rfc1952.txt" rel="noreferrer">1952</a>. 

To say that "the gzip algorithm compresses better than DEFLATE" is just nonsense. There is no gzip algorithm. And the algorithm used in the GZIP format is DEFLATE.

I have a large amount of data to move using two PHP scripts: one on the client side using a command line PHP script and other behind Apache. I POST the data to the server side and use php://input stream to save it on the web-server end. To prevent from reaching any memory limits, data is separated into 500kB chunks for each POST request. All this works fine. 

Now, to save the bandwidth and speed it up, I want to compress the data before sending and decompress when received on the other end. I found 3 pairs of functions that can do the job, but I cannot decide which one to use:

<ul>
<li><a href="http://php.net/manual/en/function.gzencode.php" rel="noreferrer"><code>gzencode</code></a> / <a href="http://php.net/manual/en/function.gzdecode.php" rel="noreferrer"><code>gzdecode</code></a></li>
<li><a href="http://php.net/manual/en/function.gzdeflate.php" rel="noreferrer"><code>gzdeflate</code></a> / <a href="http://php.net/manual/en/function.gzinflate.php" rel="noreferrer"><code>gzinflate</code></a></li>
<li><a href="http://php.net/manual/en/function.gzcompress.php" rel="noreferrer"><code>gzcompress</code></a> / <a href="http://php.net/manual/en/function.gzuncompress.php" rel="noreferrer"><code>gzuncompress</code></a></li>
</ul>

Which pair of functions would you recommend and why?

UPDATE: I just read zlib FAQ:

The gzip format (<code>gzencode</code>) was designed to retain the directory information about a single file, such as the name and last modification date. The zlib format (<code>gzcompress</code>) on the other hand was designed for in-memory and communication channel applications, and has a much more compact header and trailer and uses a faster integrity check than gzip.

Which compression method to use in PHP?

我要使用两个PHP脚本移动大量数据:一个在客户端使用命令行PHP脚本，另一个在Apache后面。我将数据发布到服务器端，并使用php://input stream将其保存在web服务器端。为了防止达到任何内存限制，对于每个POST请求，数据被分成500kB的块。所有这些都运行得很好。现在，为了节省带宽并加快速度，我希望...

问在PHP中使用哪种压缩方法？
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