如何检查文件是否gzip的COM pressed？ [英] How to check if a file is gzip compressed?

问题描述

我有需要在可以是或可以不是gzip的玉米pressed文件读取一个C / C ++程序。我知道我们可以使用来自zlib的gzread（）在读取两个COM pressed和uncom pressed文件 - 不过，我想使用zlib的功能，只有当文件是gzip的COM pressed（性能原因）。

I have a C / C++ program which needs to read in a file that may or may not be gzip compressed. I know we can use gzread() from zlib to read in both compressed and uncompressed files - however, I want to use the zlib functions ONLY if the file is gzip compressed (for performance reasons).

那么，有没有办法编程检测或者检查某个文件从C gzip压缩/ C ++？

So is there any way to programatically detect or check if a certain file is gzipped from C / C++?

推荐答案

有一个神奇的数字在文件的开头。刚看完前两个字节，并检查它们是否等于 0x1f8b 。

There is a magic number at the beginning of the file. Just read the first two bytes and check if they are equal to 0x1f8b.

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