Makefile writing rules

1 basic rules of makefile

TARGET... : DEPENDENCIES...

   COMMAND

  ...

Files produced by TARGET programs, such as executable files and object files; targets can also be actions to be performed, such as "clean".

DEPENDENCIES is the input file used to generate a target, and a target usually depends on multiple files.

A command (COMMAND) is an action performed by make, and one can have multiple commands, each on a line. Note: the starting character of each command line must be a TAB character!

If there are one or more file updates in DEPENDENCIES, COMMAND will execute, which is the core content of Makefile.

1.1 makefile uses pseudo-target .PHONY

1.2 makefile uses variables

1.2.1 makefile automation variables

2 make automatic derivation

GNU's make is very powerful, it can automatically derive the commands behind files and file dependencies, so there is no need to write similar commands after every [.o] file, because our make will automatically recognize and derive the commands.

As long as make sees a [.o] file, it automatically adds the [.c] file to the dependency. If make finds a whatever.o, then whatever.c will be a dependent file for whatever.o. And gcc-c whatever.c will also be deduced.

Common functions in 3 makefile Universal Edition 3.1 makefile

-- wildcard function

Files that match patterns in    's current directory for example: src=$ (wildcard .c)

-- notdir function

   removal path for example: $(notdir $src)

-- patsubst function

   pattern matching replacement for example: $(patsubst%.c,%.o,$src)

   is equivalent to $(src:.c=.o)

-- shell function

   executes the shell command for example: $(shell ls-d /)

3.2 Multi-level directory makefile

   there is one thing to note here, if you compile C++ files with Gmail +, the libraries used must be compiled and generated by Gmail +, otherwise you will not be able to link.

With regard to    + and gcc, although Gmail + is used to compile .cpp and gcc is used to compile .c, it can't be said that there is no overlap between the two.

   in fact, both can compile C and C++ code, but:,

   1) gcc treats .c files as C programs and Gmail + as C++ programs; for .cpp files, both think of C++ programs

   2) so, during the compilation phase, gcc is called by Gmail +, which is equivalent to C++ code, but because the gcc command does not automatically link with the libraries compiled by Gmail +, it is usually done with Gmail +.

  therefore, for convenience's sake, compile our library files with glossy +.

At the end of   , there is an article http://m.blog.csdn.net/zhujianwei31415/article/details/50725569 that I saw.

The compatibility between gcc and Gmail + compiling link library files is easy to understand.