Learning from gcc / G ++ compilers and link libraries
c ++ compiler is divided into four stages
- Precompiled
- Compile
- compilation
- link
Precompiled
Precompiled was originally part c ++ compiler, and its job is to program content before compiling some of the most trade-off process, making some statements compiled participate, while others do not participate in compiling statements.
Commonly used pre-compiler directive is:
1、包含指令：#include
2、条件指令:#if、#elif、#else、#endif、#ifdef、#ifndef
3、定义指令：#define、#undef
-
Header file will contain expanded to include the program file
- The role of conditional compilation directive is to direct and coordinate multiple choice program statement header files
, such as when you upgrade gcc version, and the need to meet the old version of the compiler, you can use conditional compilation
#if defined(__GNUC__) && (__GNUC__ >= 3 )
//balabala
#else
//balabala other
- Definition instruction can be used to prevent the same file include a plurality of times
at this stage for preprocessing the file extension is C .i, after treatment c ++ file suffix .ii
from c ++ precompiled
Compile
The main stages of compiling lexical analysis and parsing through the c ++ code is translated into assembly code
at this stage will .s .i files into file
compilation
As the name suggests is a compilation of language translation will be compiled into machine instructions
will .s files into .o files