07-07-2004
In my experience, bzip2 is usually (but not always) better with compression. gzip is my favorite, though. It faster in many cases, and compresses well enough for me.
I do think that zip, gzip, compress, and bzip2 are all different algorithms, though. I know that GNU Zip (gzip) was written specifically because the algorithm in the "compress" program wasn't "free" in the FSF meaning of the word. I was also under the impression that Zip, although it may have been based on the same mathmatics as "compress", was written independently - as was bzip2.
Check the man pages, at least for gzip and bzip2. If I remember correctly, there is some discussion of the algorithm implementation within.
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LEARN ABOUT PHP
gzcompress
GZCOMPRESS(3) 1 GZCOMPRESS(3)
gzcompress - Compress a string
SYNOPSIS
string gzcompress (string $data, [int $level = -1], [int $encoding = ZLIB_ENCODING_DEFLATE])
DESCRIPTION
This function compresses the given string using the ZLIB data format.
For details on the ZLIB compression algorithm see the document "ZLIB Compressed Data Format Specification version 3.3" (RFC 1950).
Note
This is not the same as gzip compression, which includes some header data. See gzencode(3) for gzip compression.
PARAMETERS
o $data
- The data to compress.
o $level
- The level of compression. Can be given as 0 for no compression up to 9 for maximum compression. If -1 is used, the default com-
pression of the zlib library is used which is 6.
o $encoding
- One of ZLIB_ENCODING_* constants.
RETURN VALUES
The compressed string or FALSE if an error occurred.
EXAMPLES
Example #1
gzcompress(3) example
<?php
$compressed = gzcompress('Compress me', 9);
echo $compressed;
?>
CHANGELOG
+--------+-----------------------------+
|Version | |
| | |
| | Description |
| | |
+--------+-----------------------------+
| 5.4.0 | |
| | |
| | Added $encoding parameter. |
| | |
+--------+-----------------------------+
SEE ALSO
gzdeflate(3), gzinflate(3), gzuncompress(3), gzencode(3).
PHP Documentation Group GZCOMPRESS(3)