libz

Compressing small piece of data

由 [亡魂溺海] 提交于 2020-01-15 07:26:07
问题 I have a buffer of let's say 4KB, containing data in JSON-like format. I need to add significantly more information (up to let's say 3x more) to it, but I have to fit in this small chunk of memory. I was thinking about using libZ to compress text, but I'm afraid it will not perform well since the data consists mostly of some unique substrings. What would you recommend in this situation? Thanks, Chris 回答1: Consider a fixed dictionary containing up to 32K of strings that you expect to appear in

What's the most that GZIP or DEFLATE can increase a file size?

由 生来就可爱ヽ(ⅴ＜●) 提交于 2020-01-02 03:01:57
问题 It's well known that GZIP or DEFLATE (or any compression mechanism) can increase file size sometimes. Is there a maximum (either percentage or constant) that a file can be increased? What is it? If a file is X bytes, and I'm going to gzip it, and I need to budget for file space in advance - what's the worst case scenario? UPDATE: There are two overheads: GZIP adds a header, typically 18 bytes but essentially arbitrarily long. What about DEFLATE? That can expand content by a multiplicative

How to use libz.dylib to unzip zip file?

由 北城余情 提交于 2019-12-13 18:16:58
问题 in my program i have to unzip downloaded file ... i read libz.dylib is used for that but i didn't find any documentation or examples how to do that..? any one know this... Thanks in advance.... 回答1: I'm not exactly answering your question, but you could use ZipKit. It is an Obj-C framework for using zip files. 来源： https://stackoverflow.com/questions/2729529/how-to-use-libz-dylib-to-unzip-zip-file

Error with iOS 5.1 when i use ASIHTTPRequest and SBJSON

由 ﹥＞﹥吖頭↗ 提交于 2019-12-07 04:48:18
问题 i am getting this error: Undefined symbols for architecture i386: "_OBJC_CLASS_$_ASIHTTPRequest", referenced from: objc-class-ref in FirstViewController.o "_OBJC_CLASS_$_SBJsonParser", referenced from: objc-class-ref in FirstViewController.o ld: symbol(s) not found for architecture i386 clang: error: linker command failed with exit code 1 (use -v to see invocation) Note i have added the frameworks core graphics,system configuration,mobile core services,libz.dylib,libz.1.2.5.dylib,CF Network

crc32() missing when building libzip on OSX 10.9

由 折月煮酒 提交于 2019-12-05 08:54:19
I've downloaded the latest release of libzip and am currently trying to build it on OSX and failing: Linking C shared library libzip.dylib Undefined symbols for architecture x86_64: "_crc32", referenced from: __zip_filerange_crc in zip_filerange_crc.o _crc_read in zip_source_crc.o _decrypt in zip_source_pkware.o __zip_string_crc32 in zip_string.o (maybe you meant: __zip_string_crc32) "_deflate", referenced from: _compress_read in zip_source_deflate.o (maybe you meant: _zip_source_deflate) "_deflateEnd", referenced from: _deflate_compress in zip_source_deflate.o "_deflateInit2_", referenced

What's the most that GZIP or DEFLATE can increase a file size?

由 拥有回忆 提交于 2019-12-05 04:31:00
It's well known that GZIP or DEFLATE (or any compression mechanism) can increase file size sometimes. Is there a maximum (either percentage or constant) that a file can be increased? What is it? If a file is X bytes, and I'm going to gzip it, and I need to budget for file space in advance - what's the worst case scenario? UPDATE: There are two overheads: GZIP adds a header, typically 18 bytes but essentially arbitrarily long. What about DEFLATE? That can expand content by a multiplicative factor, which I don't know. Does anyone know what it is? gzip will add a header and trailer of at least 18

is partial gz decompression possible?

由 本小妞迷上赌 提交于 2019-11-30 13:59:02
For working with images that are stored as .gz files (my image processing software can read .gz files for shorter/smaller disk time/space) I need to check the header of each file. The header is just a small struct of a fixed size at the start of each image, and for images that are not compressed, checking it is very fast. For reading the compressed images, I have no choice but to decompress the whole file and then check this header, which of course slows down my program. Would it be possible to read the first segment of a .gz file (say a couple of K), decompress this segment and read the

is partial gz decompression possible?

由 自闭症网瘾萝莉.ら 提交于 2019-11-29 14:51:36
问题 For working with images that are stored as .gz files (my image processing software can read .gz files for shorter/smaller disk time/space) I need to check the header of each file. The header is just a small struct of a fixed size at the start of each image, and for images that are not compressed, checking it is very fast. For reading the compressed images, I have no choice but to decompress the whole file and then check this header, which of course slows down my program. Would it be possible

libz.dylib versus libz.1.2.3.dylib versus libz.1.2.5.dylib

由 ε祈祈猫儿з 提交于 2019-11-27 21:02:27
I asked this in a comment but this seems like an issue that deserves its own question. I have a project that's shared between three different installations of XCode and two different installations of the iOS SDK. At the moment unifying the developers involved is not an option. When I installed the iOS 5 Beta and XCode 4.2 libz.1.2.3.dylib was nowhere to be found. I discovered that linking against libz.1.2.5.dylib handled this but this was not compatible with the other active installations of XCode and the iOS SDK. I researched this online and discovered the above suggestion and this suggestion

libz.dylib versus libz.1.2.3.dylib versus libz.1.2.5.dylib

由 让人想犯罪 __ 提交于 2019-11-26 23:00:15
问题 I asked this in a comment but this seems like an issue that deserves its own question. I have a project that's shared between three different installations of XCode and two different installations of the iOS SDK. At the moment unifying the developers involved is not an option. When I installed the iOS 5 Beta and XCode 4.2 libz.1.2.3.dylib was nowhere to be found. I discovered that linking against libz.1.2.5.dylib handled this but this was not compatible with the other active installations of
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