About Library (function library), dynamic library and static library

Make dynamic library , Static library , I have some understanding , At the same time, it is also convenient for me to check my notes in the future , If there is a mistake , Please comment , thank you ！
library ( function library )：
Function library is a collection of functions with certain functions established by the system . The library stores the name of the function and the corresponding object code , And relocation information required during connection . Users can also create their own user function library according to their own needs . ( Convenient to call , And encrypt the code )
Be careful ： Function functions are stored in the library , Don't put main Functions are encapsulated .
Dynamic library （libname.so）：
characteristic ：
(1) When compiling an executable using functions in the library , It does not compile the code in the library . Programs compiled with dynamic libraries are relatively small .
(2) Executable compiled by dynamic library , This dynamic library is required in the system environment variable during execution , Otherwise, it cannot run .
Make ：gcc -shared -fPIC -o lib Library name .so .c .c …
.c .c …： All function functions .c file
shared： To generate .so Dynamic library files
-fPIC： -fPIC Works in the compilation phase , Tell the compiler to generate location independent code (Position-Independent Code), In the generated code , No absolute address , All use relative addresses , Therefore, the code can be loaded anywhere in memory by the loader , Can be executed correctly . This is what shared libraries require , When the shared library is loaded , The location in memory is not fixed .
Each library has one or more corresponding header files
（1） compile
gcc .c -o Executable file name -I( Big i) Follow file path -L Follow the library file path -l( A lowercase letter l) Library name
.c : The main function .c file
Executable file name : Suggested main function name _so, It is convenient to know which file is generated in the future
-I( Big i) Follow file path : Link header file
-l( A lowercase letter l) Library name ： -l There is no space between the database name and the previous one
Library name ： Do not prefix lib, And no suffix .so
This dynamic library is available in the system environment variable Copy the dynamic library to /lib or /usr/lib in
（2） perform
./ Executable file name
Static library （libmame.a）：
characteristic ：
(1) When compiling an executable using functions in the library , Will replace Code is compiled into . Programs compiled with static libraries are relatively large .
(2) Executable compiled by static library , This library is not required in the system environment variable during execution , It can also run .
Make ：gcc .c -o .o -c
①.c: every last .c, Can only be generated one by one .o file
②ar cr lib Library name .a .o .o … -c
ar ： Packaging tools Can be used to create , Modify library file , Extract from the library file Of .o modular
c ： One option , Represents creating a library , Create a library file whether it exists or not .
r ： One option , It means that you will .o Insert the module into the library .
.o .o …: All function functions .c File generated .o Redirectable files
（1） compile
gcc .c -o Executable file name -I( Big i) Follow file path -L Follow the library file path -l( A lowercase letter l) Library name -static( See the following precautions )
Executable file name : Suggested main function name _a, It is convenient to know which file is generated in the future
-I( Big i) Follow file path : Link header file
-l( A lowercase letter l) Library name ： -l There is no space between the database name and the previous one
Library name ： Do not prefix lib, And no suffix .a
Be careful ： There are dynamic libraries and static libraries under the current path , The dynamic library will be compiled by default first , In order to compile with a static library, you need to add -static
（2） perform
./ Executable file name