What does ‘const static’ mean in C and C++?

by

A lot of people gave the basic answer but nobody pointed out that in C++ const defaults to static at namespace level (and some gave wrong information). See the C++98 standard section 3.5.3.

First some background:

Translation unit: A source file after the pre-processor (recursively) included all its include files.

Static linkage: A symbol is only available within its translation unit.

External linkage: A symbol is available from other translation units.

At namespace level

This includes the global namespace aka global variables. 

static const int sci = 0; // sci is explicitly static
const int ci = 1;         // ci is implicitly static
extern const int eci = 2; // eci is explicitly extern
extern int ei = 3;        // ei is explicitly extern
int i = 4;                // i is implicitly extern
static int si = 5;        // si is explicitly static

At function level

static means the value is maintained between function calls.
The semantics of function static variables is similar to global variables in that they reside in the program’s data-segment (and not the stack or the heap), see this question for more details about static variables’ lifetime.

At class level

static means the value is shared between all instances of the class and const means it doesn’t change.

More Related Contents:

  1. Why should I use a pointer rather than the object itself?
  2. How to add additional libraries to Visual Studio project?
  3. CMake error at CMakeLists.txt:30 (project): No CMAKE_C_COMPILER could be found
  4. Variable initialization in C++
  5. How to use the Qt’s PIMPL idiom?
  6. the procedure entry point __gxx_personality_v0 could not be located
  7. problem sorting using member function as comparator
  8. Constants and compiler optimization in C++
  9. C++: what regex library should I use? [closed]
  10. pinpointing “conditional jump or move depends on uninitialized value(s)” valgrind message
  11. Mismatch Detected for ‘RuntimeLibrary’
  12. Is adding to a “char *” pointer UB, when it doesn’t actually point to a char array?
  13. Allocating more memory than there exists using malloc
  14. How to detect existence of a class using SFINAE?
  15. std::unique_lock or std::lock_guard?
  16. delete[] an array of objects
  17. write and read string to binary file C++
  18. Which C++ signals/slots library should I choose? [closed]
  19. How do I get the application data path in Windows using C++?
  20. constexpr function parameters as template arguments
  21. Nullable values in C++
  22. Should I pass a shared_ptr by reference? [duplicate]
  23. What does ## in a #define mean?
  24. How to detect whether Windows is shutting down or restarting
  25. Difference between steady_clock vs system_clock?
  26. Visual Studio debugger error: Unable to start program Specified file cannot be found
  27. Visual Studio Warning C4996
  28. signal handler function in multithreaded environment
  29. Why does (i|o)fstream take a const char* parameter for a file name?
  30. Is it possible to have a pointer literal?

Leave a Comment