Shulou(Shulou.com)06/01 Report--

When it comes to inline, you may still stop at the C++ scriptures more than ten years ago or even more than twenty years ago. C++ has inline keywords and is even used to distinguish it from c. c99 began to introduce inline c, gcc earlier than c99 to achieve inline support, vc c no keyword inline, inline can only be used for c++, but there is another keyword__inline, but if you want to use vc to compile gcc c code, encountered cl complaints do not recognize inline, as long as inline in the pre-compiled macro defined as__inline can also be.

There is also a noinline in the gcc compiler attribute. Why would there be a noinline when there is an inline? If you don't use inline, isn't it equal to noinline? There is also the always_inline attribute. Because in practice, all definitions of inline are not necessarily inline, and the final decision is made by the gcc compiler, but your declaration will affect its decision. Similarly, if you don't define inline, functions don't necessarily have to be inline. Compilers usually decide to inline some functions for you in optimization, regardless of the size of the function. The noinline and always_inline attributes are literally that.

Just recently debugged ffmpeg code, encountered an example, used as an example:

FFMPEG is a C code project.

avformat_write_header is a ten-line function that calls other functions.

init_muxer is a large static function, not defined inline, but inline into a small function (avformat_write_header).

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