Linux creates static libraries and uses of static libraries

Directory:
1 manually establishing static libraries 2 use of static libraries 3 creating a static library from a makefile file
1 Creating a static library manually will create a simple static library
-1: Compile the required source files into the target file
------Helpguy.h

#ifndef __helpguy_h__#define __helpguy_h__#include <stdlib.h> #include <stdio.h> #include <unistd.h >void err_msg (const char* errmsg, ...); #endif//__helpguy_h__

------helpguy.cc

#include "helpguy.h" #include <stdarg.h> #include <errno.h> #include <string.h>void exit_msg (const char* errmsg, ...) {     va_list ap;         Va_start (AP, errmsg);     int errno_save = errno;     Char buf[1024];     vsnprintf (buf, sizeof (BUF)-1, ErrMsg, AP);     if (Errno_save! = 0)     {          int len = strlen (BUF);          snprintf (buf + len, sizeof (BUF)-Len-1, ": (%d)%s",                    Errno_save, Strerror (Errno_save));     }     strcat (buf, "\ n");     Output     fflush (stdout);     Fputs (buf, stderr);     Fflush (stderr);     Va_end (AP);     Exit (1);}

Compile:
g++-C helpguy.cc//Generate file: HELPGUY.O
2 Create the target file as a static library file the general static library name is LIBXXX.A, and when used, add-lxxx at the end of the command line, and the compilation will look for LIBXXX.A or libxxx.so files.
AR CRS libhelpguy.a HELPGUY.O//Build library file: libhelpguy.a
2 Use of static libraries
------Test File main.cc

#include "Helpguy.h" #include <iostream>int main (int argc, char** argv) {     std::cout << "Please enter Positive integer: ";         int value;     Std::cin >> value;     if (value <= 0)          exit_msg ("Need positive integer");     Std::cout << "The value is:" << value << Std::endl;     Std::cout << "OK" << Std::endl;     return 0;}

Compile:
g++-o main main.cc-l.-lhelpguy//Generate: Main file./main When you enter a non-integer, the exit_msg is called.
-L. Tell the compiler to wash "." In the current directory. Looking for a library file named Libhelpguy.a or libhelpguy.so
3 Creating a static library from a makefile file
-----Makefile
Cflags=-g-d__stdc_format_macros-wall-werror-i.
Libs=-lrt-pthread

libhelpguy.a:helpguy.o
AR CRS [email protected] $^
chmod u+x [email protected]

helpguy.o:helpguy.cc
g++-o [email protected]-C $< $ (CFLAGS)

Clean
RM-RF HELPGUY.O

You can create a static library file by entering the make command:
makeg++-o helpguy.o-c helpguy.cc-g-d__stdc_format_macros-wall-werror-i.
AR CRS libhelpguy.a HELPGUY.O
chmod u+x libhelpguy.a

If you have more than one. o file, you can continue adding it behind LIBHELPGUY.A: and then mimic helpguy.o to add the command to generate the target file.

Linux creates static libraries and uses of static libraries