gcc的几个妙用

gcc本质是完结程序的编译和链接，程序的编译是指从一种文件类型转换到另一种文件类型的进程。一个C言语程序转换为可执行程序的根本进程如下：

1、编写程序（vi，emacs等软件）

2、程序预编译（cpp）

3、编译成汇编程序（cc）

4、汇编程序（as）

5、链接程序（ld）

其间的这些进程都现已被gcc包括，咱们在实践的编译进程中选用了gcc main.c -o main.exe即可完成一个程序的编译和链接。并不需求一步一步的完成，可是咱们在剖析的进程中又有必要留意一个C言语文件的处理进程以及相应的处理程序。

关于gcc的根本意义用法就不再具体的说明晰，我觉得最简略的运用方法是经过软件的help学习软件。

[gong@Gong-Computer test]$ gcc –help
Usage: gcc [options] file…
Options:
-pass-exit-codes Exit with highest error code from a phase
–help Display this information
–target-help Display target specific command line options
–help={target|optimizers|warnings|params|[^]{joined|separate|undocumented}}[,…]
Display specific types of command line options
(Use -v –help to display command line options of sub-processes)
–version Display compiler version information
-dumpspecs Display all of the built in spec strings
-dumpversion Display the version of the compiler
-dumpmachine Display the compilers target processor
-print-search-dirs Display the directories in the compilers search path
-print-libgcc-file-name Display the name of the compilers companion library
-print-file-name= Display the full path to library -print-prog-name= Display the full path to compiler component -print-multi-directory Display the root directory for versions of libgcc
-print-multi-lib Display the mapping between command line options and
multiple library search directories
-print-multi-os-directory Display the relative path to OS libraries
-print-sysroot Display the target libraries directory
-print-sysroot-headers-suffix Display the sysroot suffix used to find headers
-Wa, Pass comma-separated on to the assembler
-Wp, Pass comma-separated on to the preprocessor
-Wl, Pass comma-separated on to the linker
-Xassembler Pass on to the assembler
-Xpreprocessor Pass on to the preprocessor
-Xlinker Pass on to the linker
-combine Pass multiple source files to compiler at once
-save-temps Do not delete intermediate files
-save-temps= Do not delete intermediate files
-no-canonical-prefixes Do not canonicalize paths when building relative
prefixes to other gcc components
-pipe Use pipes rather than intermediate files
-time Time the execution of each subprocess
-specs= Override built-in specs with the contents of
-std= Assume that the input sources are for
–sysroot= Use as the root directory for headers
and libraries
-B Add to the compilers search paths
-b Run gcc for target , if installed
-V Run gcc version number , if installed
-v Display the programs invoked by the compiler
-### Like -v but options quoted and commands not executed
-E Preprocess only; do not compile, assemble or link
-S Compile only; do not assemble or link
-c Compile and assemble, but do not link
-o Place the output into
-x Specify the language of the following input files
Permissible languages include: c c++ assembler none
none means revert to the default behavior of
guessing the language based on the files extension

Options starting with -g, -f, -m, -O, -W, or –param are automatically
passed on to the various sub-processes invoked by gcc. In order to pass
other options on to these processes the -W options must be used.

For bug reporting instructions, please see:
.

从上面的成果能够知道根本的用法。

可是仍是有几个需求留意的当地，这也是咱们学习gcc时不常常运用，但又十分有用的几个用法。

1、选用gcc完成预编译，预编译能够完成代码的查看，特别是宏界说的查看，经过预编译查看实践的代码是否犯错，这是十分有用的查看方法。

因为预编译今后宏界说被扩展了，这时对源码的剖析就能找出代码宏界说等是否存在过错，特别时一些不容易发现的过错。

根本的完成方法为:gcc -E file.c > file.pre.c

[gong@Gong-Computer Example]$ vi main.c

选用重定向的方法改动输出流，便于查看过错地点。
[gong@Gong-Computer Example]$ gcc -E main.c > main.pre.c

[gong@Gong-Computer Example]$ vi main.pre.c

从上面的成果能够发现咱们的宏现已完成了扩展。经过剖析宏的扩展能够剖析代码是否正确。