I'm a begginer with C++ and I'm trying to practice with headers and Namespaces. Specifically I wanted to create different modules with their own namespaces so I can use one program to go through others without mixing the names. I used the advice from this other question and it works fine with functions but when I get to a constant I get an "redefining error"
The 2 relevant files:
//mainHeader.h
#pragma once
#include <iostream>
#include <string>
#include <sstream>
namespace primes {
int isPrime(int a);
}
namespace CONST {
typedef unsigned long long int LONGINT;
double pi;
}
namespace E1 {
int main();
}
namespace E2 {
int main();
}
//CONSTANTS.cpp
#include "mainHeader.h"
namespace CONST{
pi = 3.14159265;
typedef unsigned long long int LONGINT;
}
Of course there's a main function that is mostly empty and 2 other .cpp files that are working fine. It compiled and worked as wanted before I created the CONSTANTS.cpp and decided to test the same for constants
The problem is that this code tells me that pi in CONSTANTS.cpp isn't defined correctly:
missing type specifier - int assumed. Note: C++ does not support default-int
However, if I add the type to the definition in CONSTANTS
it throws that redefine error.
> e1.obj : error LNK2005: "double CONST::pi" (?pi@CONST@@3NA) already defined in CONSTANTS.obj
> e2.obj : error LNK2005: "double CONST::pi" (?pi@CONST@@3NA) already defined in CONSTANTS.obj
> e3.obj : error LNK2005: "double CONST::pi" (?pi@CONST@@3NA) already defined in CONSTANTS.obj
That sounds like the declaration in mainHeader.h is the problem but if I change it or take it out I get:
> ...\e3.cpp(34): error C2039: 'pi': is not a member of 'CONST'
> ...\mainHeader.h(12): note: see declaration of 'CONST'
> ...\e3.cpp(34): error C2065: 'pi': undeclared identifier
So I don't understand. If I take it out it doesn't find any definition, if I add it, it finds more than one.
The code for e1.cpp just in case, although I think the only problem would be the first line:
#include "mainHeader.h"
namespace E1 {
int main()
{
int ans = 0;
for (int i = 0; i < 1000; i++) {
if ((i % 3 == 0) || (i % 5 == 0)) ans += i;
}
std::cout << ans << std::endl;
return 0;
}
}
I tried what I think is every combination of definition and initialization. I used. I tried adding #pragma once to CONSTANTS.cpp, to e1.cpp, I even tried using
#ifndef CONST_H ... #endif
I added #include "mainHeader.h" to each eX.cpp file because there are functions that I want to share between them. Like for example primes.cpp will have some functions that some eX.cpp files will use, so I need to be able to call them.
Any help will be appreciated
