G++ tutorial

What is G++?

It's a cpp compiler which is a part from GNU Compiler Collection(gcc)

What we will do in this post?
We will write a simple C++ and C code then Compile them using gcc

Tools we need:
Text Editor (I use vim)
Command line knowledge
Linux distro

LETS'S START

Step 1:
write the main file which will be a C file

#include<stdio.h>
#include"reciprocal.hpp"

int main(char argc, char **argv){
    int i;
    i = atoi(argv[1]);
    printf("The reciprocal of %d is %g\n", i, reciprocal(i));
    return 0;
}

 Don't do anything else, as u can c that there is a header file called  reciprocal.hpp
so we will need to write the implementation of this header file (Source code(.cpp) and header file(.hpp))

First write the header file (reciprocal.hpp):

#ifdef __cplusplus
extern "C"{
#endif
    extern double reciprocal(int i);
#ifdef __cplusplus
}
#endif

and save  it, then open another file which will be the source code (reciprocal.cpp):

#include<cassert>
#include"reciprocal.hpp"

double reciprocal(int i){
    assert(i != 0);
    return 1.0/i;
}

 Now we have three files, Two source files (main.c and reciprocal.cpp) and one header file (reciprocal.hpp) so let's compile them.
First of all notice that reciprocal.hpp is included in both of the source files so we will need to compile it first (Actually we will compile the source file reciprocal.cpp) by this command

 g++ -c -I reciprocal.hpp reciprocal.cpp

 g++ is the compiler command (For C++)
-c an option to tell the compiler that we need only the object file
-I an option to include the file reciprocal.hpp
Second we will need to compile the main.c file by this command

gcc -c -I reciprocal.hpp main.c

again gcc is the command name (For C)
and the others are the same

Now we need to link the object files to create the executeable file

    g++ -o reciprocal main.o reciprocal.o

*Note that we use g++ to compile the files although the main file is a C file , that's it if u have many source files written in both C & C++ then you should use g++

Debugging:
We can see the debugging informaion by invoking the -g option in every command

Copy writes Advanced Linux Programming by Mark Mitchell, Jeffrey Oldham, and Alex Samuel