C++ good reference:  http://www.cplusplus.com/reference/


  1 //namesp.cpp -- demo namespace, by tsaiwn@csie.nctu.edu.tw
  2 #include <stdio.h>
  3 #include <iostream>
  4 //Note that ALL C++ library are in namespace std
  5 // using namespace std;  // 若不寫則所有C++程式庫的都要寫成 std::
  6 
  7 namespace Taiwan {
  8    void haha( ) { printf("haha haha 哈!\n"); }
  9 }
 10 namespace japan {
 11    void haha( ) { printf("Dou Dou Yo Lou Si Ku!\n"); }
 12    void bye( ) { printf("Sa Yo Na La!\n"); }
 13 }
 14 namespace USA {
 15    void haha( ) { printf("won won How do you do!\n"); }
 16    void bye( ) { printf("Bye! See U!\n"); }
 17 }
 18 namespace Taiwan {   //注意這也是在 Taiwan
 19    void bye( ) { printf("Good bye! 再見!!\n"); }
 20 }
 21 
 22 void bye(int x) { printf("BBB BBB BBBBB!\n"); } //name overloading
 23 
 24 using namespace Taiwan;
 25 //using namespace USA;
 26 //using namespace japan;
 27 int main( ) {
 28    // cout << "Welcome ..." << endl; // 若有 using namespace std;
 29    std::cout << "Welcome ..." << std::endl;
 30    printf("Now do    japan::haha( );\n");
 31    japan::haha( );
 32    printf("\n");
 33    printf("Now do    USA::haha( );\n");
 34    USA::haha( );
 35    printf("Now do    USA::bye( );\n");
 36    USA::bye( );
 37    printf("=== now do haha( ); bye( );\n");
 38    haha( );
 39    bye( );
 40    printf("Note the using namespace ...\n");
 41    ::bye(38);   // this function is in default namespace
 42    return 0;
 43 }
 44 /******
 45 D:\COURSE\OOP\ppnt>g++ namesp.cpp
 46 
 47 D:\COURSE\OOP\ppnt>a
 48 Welcome ...
 49 Now do    japan::haha( );
 50 Dou Dou Yo Lou Si Ku!
 51 
 52 Now do    USA::haha( );
 53 won won How do you do!
 54 Now do    USA::bye( );
 55 Bye! See U!
 56 === now do haha( ); bye( );
 57 haha haha 哈!
 58 Good bye! 再見!!
 59 Note the using namespace ...
 60 BBB BBB BBBBB!
 61 
 62 ********************************/