The C++ namespace: the namespace with 'using' directive C++ program example

 

Compiler: Visual C++ Express Edition 2005

Compiled on Platform: Windows XP Pro SP2

Header file: Standard

Additional library: none/default

Additional project setting: Set project to be compiled as C++

Project -> your_project_name Properties -> Configuration Properties -> C/C++ -> Advanced -> Compiled As: Compiled as C++ Code (/TP)

Other info: none

To do: Displaying some data to demonstrate how to use the 'using' directive for namespace in C++ programming

To show: How to use the namespace with the 'using' directive in C++ programming

 

// namespace with 'using' directive.

#include <iostream>

using namespace std;

 

namespace SampleOne

{

double p = 10.34;

}

 

namespace SampleTwo

{

using namespace SampleOne;

double q = 77.12;

 

namespace InSampleTwo

{

double r = 34.725;

}

}

 

int main(void)

{

// this directive gives you everything declared in SampleTwo

using namespace SampleTwo;

// this directive gives you only InSampleTwo

using namespace SampleTwo::InSampleTwo;

// local declaration, take precedence

double p = 23.11;

 

cout<<"p = "<<p<<endl;

cout<<"q = "<<q<<endl;

cout<<"r = "<<r<<endl;

 

return 0;

}

 

Output example:

 

p = 23.11

q = 77.12

r = 34.725

Press any key to continue . . .

 

 

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