How to create a new library in C ++

Two types of libraries will be explained: static and shared. Below is an example of creating both command-line in Linux .

Static library: Used in compilation

main.cpp

#include "libprint.h"

int main(){

   //Função guardada numa biblioteca estática
   print_ola("Rafael");
}

libprint.h (Static Library Header) - it's good to create a header file for your library.

#ifndef LIBPRINT_H
#define LIBPRINT_H

   void print_ola(const char *);

#endif

printola.cpp (Code of your static library)

#include "libprint.h"
#include <iostream>

void print_ola(const char *nome){

   std::cout << "Olá, " <<  nome << "!" << std::endl;
}

Steps to create the static library:

Generate the object code of printola.cpp: g++ -c printola.cpp . Now package the object code in the form of a library:

ar crv libprintola.a printola.o

Compilation and execution:

g++ main.cpp -o programa libprintola.a

./programa

Exit: Hello, Rafael!

Shared Libraries: - (with the same old files!)

g++ -c -fpic printola.cpp creates the object object code that can be used as shared.

g++ -shared -o libprintola.so printola.o creates your shared library named libprintola.so !

Testing: g++ -L. -Wl,-rpath=. -Wall -o programa main.cpp -lprintola

That should display the same result. (but beware! each works differently!)