Question

How to use namespace in C++

Answer 1

#include <iostream>

namespace A {
    void function() {
        std::cout << "namespace A function()";
    }
}
 
namespace B {
    void function() {
         std::cout << "namespace B function()";
    }
}

using namespace A;

int main ()
{
    function();
}



/*
run:

namespace A function()

*/

 

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Answer 2

#include <iostream>

namespace A {
    void function() {
        std::cout << "namespace A function()";
    }
    namespace B {
        void function() {
            std::cout << "namespace B function()";
        }
    }
}
 


using namespace A::B;

int main ()
{
    function();
}



/*
run:

namespace B function()

*/

 

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Answer 3

#include <iostream>

namespace A {
    void function() {
        std::cout << "namespace A function()" << "\n";
    }
}
 
namespace B {
    void function() {
         std::cout << "namespace B function()" << "\n";
    }
}

int main ()
{
    A::function();
    B::function();
}




/*
run:

namespace A function()
namespace B function()

*/

 

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Answer 4

#include <iostream>

namespace A {
    int num = 120;
}
 
int num = 88; // Global;

int main ()
{
    std::cout << num << '\n';
    std::cout << A::num << '\n';
}




/*
run:

88
120

*/

 

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Answer 5

#include <iostream>

namespace A {
    class Example {
    public:
        void print() {
            std::cout << "namespace A - Example - print()" << "\n";
        }
    };
}

namespace B {
    class Example {
    public:
        void print() {
            std::cout << "namespace B - Example - print()" << "\n";
        }
    };
}
 

int main ()
{
    A::Example obj1;
    obj1.print();
    
    B::Example obj2;
    obj2.print();
}




/*
run:

namespace A - Example - print()
namespace B - Example - print()

*/

 

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