How to implement static class member functions in cpp file

Question

Is it possible to implement static class member functions in   cpp file instead of doing it in the header file    Are all static functions always inline

User · Answer

The  include directive literally means  copy all the data in that file to this spot   So when you include the header file  it s textually within the code file  and everything in it will be there  give or take the effect of other directives or macro replacements  when the code file  now called the compilation unit or translation unit  is handed off from the preprocessor module to the compiler module   Which means the declaration and definition of your static member function were really in the same file all along

User · Answer

It is   test hpp   class A   public      static int a int i        test cpp    include  lt iostream gt   include  test hpp    int A  a int i        return i   2     using namespace std  int main         cout  lt  lt  A  a 4   lt  lt  endl      They re not always inline  no  but the compiler can make them

User · Answer

Sure You can  I d say that You should   This article may be usefull  http   www learncpp com cpp-tutorial 812-static-member-functions

User · Answer

In your header file say foo h  class Foo      public          static void someFunction params            other stuff     In your implementation file say foo cpp   include  foo h   void Foo  someFunction params            Implementation of someFunction     Very Important  Just make sure you don t use the static keyword in your method signature when you are implementing the static function in your implementation file   Good Luck

User · Answer

Yes you can define static member functions in   cpp file  If you define it in the header  compiler will by default treat it as inline  However  it does not mean separate copies of the static member function will exist in the executable  Please follow this post to learn more about this   Are static member functions in c   copied in multiple translation units

User · Answer

crobar  you are right that there is a dearth of multi-file examples  so I decided to share the following in the hopes that it helps others                  main cpp                  include  lt iostream gt    include  UseSomething h   include  Something h   int main         UseSomething y      std  cout  lt  lt  y getValue    lt  lt    n                     Something h                  ifndef SOMETHING H   define SOMETHING H   class Something   private      static int s value  public      static int getValue     return s value       static member function     endif                 Something cpp                  include  Something h   int Something  s value   1     initializer                 UseSomething h                  ifndef USESOMETHING H   define USESOMETHING H   class UseSomething   public      int getValue         endif                 UseSomething cpp                  include  UseSomething h   include  Something h   int UseSomething  getValue         return Something  getValue

User · Answer

helper hxx  class helper    public      static void fn1             defined in header itself             fn2 defined in src file helper cxx       static void fn2          helper cxx   include  helper hxx  void helper  fn2          fn2 defined in helper cxx         do something        A cxx   include  helper hxx  A  foo       helper  fn1       helper  fn2        To know more about how c   handles static functions visit  Are static member functions in c   copied in multiple translation units

User · Answer

Try this   header hxx   class CFoo   public       static bool IsThisThingOn         class cxx    include  header hxx  bool CFoo  IsThisThingOn      note  no static keyword here       return true

[c++] How to implement static class member functions in *.cpp file?

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