How to create a new library in C++

Question

I would like to know how to create a new library in C++. if one can give an example, it can be a widespread example.

Answer 1

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

Static library: Used in the compilation

main.cpp

#include "libprint.h"

int main(){

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

libprint. h (Static library header) - it is good to create a header file for your library.

#ifndef LIBPRINT_H
#define LIBPRINT_H

   void print_ola(const char *);

#endif

printola.cpp (Code from your static library)

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

void print_ola(const char *nome){

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

Steps to create static library:

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

ar crv libprintola.a printola.o

Ready! You already have a static library called libprintola. a! (more object codes can be inserted into a single library ex: ar crv libprintola.a printola.o printalgo.o etc).

Compilation and execution:

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

./programa

Exit: Hello, Rafael!

Bibliotecas Compartilhadas: - (with the same previous files!)

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

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

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

Which should display the same result. (but watch out! each one works differently!)