C + + header file Precompilation and namespace usage methods

Precompiled use of macro directives, pre-compilation of header files for multiple files

Header File Code:

#include <iostream>#ifndef xb_h// pre-compilation to determine whether Xb_h code snippet is executed #define xb_h//  xb_h Code snippet begins namespace  xb{    int op (intint  y)    {        return x*y;    }} #endif // Xb_h End of code snippet

Source file Code:

#include <iostream>"xb.h"// header file int  Main ( ) {    std::cout<<xb::op (ten); // namespaces how    to use System ("pause");     return 0 ;}

C + + header file Precompilation and namespace usage methods