Gcc parameters commonly used under Linux

First of all, gcc and g++ are gnu c and c++ compilers respectively, and they generally need to be divided into four steps when compiling:

1 preprocessing For cpp will generate the .i file, use the preprocessor cpp

2 to convert the preprocessed file to assembly language, generate the .s file, use the compiler egcs

3 The assembly file becomes the target file, that is, the machine code is generated. Here is the .o file generated. Use the assembler as

4 to connect the object code, generate the executable program, and use the connector ld

The main parameters are:

-x language filename It is the language used to set the file. At this time, the suffix name is invalid. Although we agree that the c language suffix is ​​.c, the c++ language suffix name is. Cpp, but at this point we can use the suffix name at will. Commonly available parameters are: c, objective-c, c-header, c++, cpp-output, assembler, assembler-with-cpp. For example, we can use the command cpp -xc hello.xin

-x none filename This is to close the previous option, let gcc automatically determine the file type according to the suffix of the file name, such as gcc -xc hello.xin -x none Hi.c

-c is only to activate preprocessing, compiling and assembly, that is, it only makes the program into obj file, we can use gcc -c hello.c to generate .o obj file

-S only activates preprocessing and compilation, and can compile files into assembly code. For example, our gcc -S hello.c will generate assembly code for .s, which we can view using a text editor.

-E only activates preprocessing, this does not generate files, we need to redirect it to an output file, such as gcc -E hello.c > xin.txt or gcc -E hello.c | More to see.

-o specifies the target name. The default gcc compiled file is a.out. We can use gcc -o hello hello.c.

-pipe uses pipes instead of temporary files in compilation. When using non-gnu assembly tools, you may have problems.

-undef cancels the definition of any non-standard macros

-Idir When we use #include, gcc will first look up the header files we have created in the current directory. If not found, It will go to the default header directory file. If you specify a directory with -I, it will first look in the directory we specified, and then go to the regular directory to find.

-I- is the function to cancel the previous parameter, generally used after -Idir.

-C does not delete the comment information when pre-processing, generally used with -E, it is convenient when analyzing the program

-M generates file-related information, including the target file Dependent on all source code, we can use gcc -M hello.c to test

-MM and -M are the same, but he ignores the dependencies caused by #include <file>

-MD is the same as -M, but the output is imported into the .d file.

-MMD is the same as -MM, and the output is imported into the .d file.

-library is specified to compile The library to use when.

-Ldir specifies the path to the search library at compile time, where dir is the name of our directory.

-O0, -O1, -O2, -O3 are the four levels of compiler optimization options, where -O0 means no optimization, -O1 is the default value, and -O3 has the highest optimization level. >

-g is just a compiler. When compiling, it generates debugging information.

-gstabs which generates debugging information in stabs format, but does not contain gdb debugging information.

-ggdb will generate Gdb debugging information

-static will prohibit the use of dynamic libraries, so the compiled things are generally very large

-share will try to use dynamic libraries, so the generated files are small, but need to use Dynamic library

-traditional apprentices let the compiler support traditional C language features