function parameter evaluation order

by

C and C++ are two completely different languages; don’t assume the same rules always apply to both. In the case of parameter evaluation order, however:

C99:

6.5.2.2 Function calls
…
10 The order of evaluation of the function designator, the actual arguments, and
subexpressions within the actual arguments is unspecified, but there is a sequence point
before the actual call.

[Edit]
C11 (draft):

6.5.2.2 Function calls
…
10 There is a sequence point after the evaluations of the function designator and the actual
arguments but before the actual call. Every evaluation in the calling function (including
other function calls) that is not otherwise specifically sequenced before or after the
execution of the body of the called function is indeterminately sequenced with respect to
the execution of the called function.94)
…
94) In other words, function executions do not ‘‘interleave’’ with each other.

C++:

5.2.2 Function call
…
8 The order of evaluation of arguments is unspecified. All side effects of argument expression evaluations take effect
before the function is entered. The order of evaluation of the postfix expression and the argument expression list is
unspecified.

Neither standard mandates the use of the hardware stack for passing function parameters; that’s an implementation detail. The C++ standard uses the term “unwinding the stack” to describe calling destructors for automatically created objects on the path from a try block to a throw-expression, but that’s it. Most popular architectures do pass parameters via a hardware stack, but it’s not universal.

[Edit]

I am getting confusing information from the books.

This is not in the least surprising, since easily 90% of books written about C are simply crap.

While the language standard isn’t a great resource for learning either C or C++, it’s good to have handy for questions like this. The official™ standards documents cost real money, but there are drafts that are freely available online, and should be good enough for most purposes.

The latest C99 draft (with updates since original publication) is available here. The latest pre-publication C11 draft (which was officially ratified last year) is available here. And a publicly availble draft of the C++ language is available here, although it has an explicit disclaimer that some of the information is incomplete or incorrect.

More Related Contents:

  1. Does the stream operator exist for class member functions?
  2. Is segmentation fault actual undefined behavior when we refer to a non-static data-member
  3. C++ Matrix Class
  4. What is memory fragmentation?
  5. Code outside functions
  6. undefined reference to boost::system::system_category() when compiling
  7. Purpose of Header guards
  8. Dividing two integers to produce a float result [duplicate]
  9. How to write a type trait `is_container` or `is_vector`?
  10. What is the difference between “new” and “malloc” and “calloc” in C++? [duplicate]
  11. boost::spirit::qi duplicate parsing on the output
  12. Error LNK1104: cannot open file ‘Debug\MyProjectLib.lib’
  13. Get DLL path at runtime
  14. Meaning of U suffix
  15. Compile-time assertion?
  16. How to get a Windows symbol server set up
  17. Can we see the template instantiated code by C++ compiler
  18. static vs non-static variables in namespace
  19. How is vector implemented in C++
  20. Pros and cons of using nested C++ classes and enumerations?
  21. C++ : friend declaration ‘declares a non-template function
  22. Specify template parameters at runtime
  23. C++/C function pointers that return void*
  24. How does #include work in C++?
  25. Difference between const. pointer and reference?
  26. C++11 operator”” with double parameter
  27. Some clarification needed about synchronous versus asynchronous asio operations
  28. What can make C++ RTTI undesirable to use?
  29. Lambda Expression vs Functor in C++
  30. How to convert a const char * to std::string [duplicate]

Leave a Comment