Namespace issue in C++

Question

I have two files Sample.cpp and Main_file.cpp. Sample.cpp has only one namespace n1 which contains the definition of int variable x. I want to print this variable x in my main_file.cpp. How do I go about doing this?

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//Sample.cpp_BEGINS

namespace n1
{
    int x=10;
}
//Sample.cpp_ENDS

//Main_FILE_BEGINS

void main()
{
    print x;
}
//MAIN_FILE_ENDS

Thank you for any help you can provide.

Answer 1

You use the fully qualified name of the variable:

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int main()
{   
     n1::x = 10;

     return 0;
}

Answer 2

To make n1::x accessible from main.cpp you'll probably want to create and include sample.h:

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// sample.h
#ifndef SAMPLE_H
#define SAMPLE_H

namespace n1
{
    extern int x;
}
#endif

---

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// sample.cpp
#include "sample.h"

namespace n1
{
    int x = 42;
}

---

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

int main()
{   
     std::cout << "n1::x is " << n1::x;
}

If you prefer not to create a header file you can also do this in your main.cpp:

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#include <iostream>

namespace n1
{
    extern int x;
}    

int main()
{   
     std::cout << "n1::x is " << n1::x;
}

Answer 3

add a line using namespace n1 in main or you can also do as @als suggested.