declaration

I am used to declaring variadic functions like this: int f(int n, ...); When reading The C++ Programming Language I found that the declarations in the book omit the comma: int f(int n...); // the comma has been omitted It seems like this syntax is C++ specific as I get this error when I try to compile it using a C compiler: test.c:1:12: error: expected ‘;’, ‘,’ or ‘)’ before ‘...’ token int f(int n...); Is there any difference between writing int f(int n, ...) and int f(int n... )? Why was this syntax added C++? kfsone According to § 8.3.5.4 of the C++ standard ( current draft ): Where

In my example below, why do I have to fully qualify the name of the free function in the cpp to avoid linker errors and why does it work for the class function without? Can you explain the difference? ctest.h: namespace Test { int FreeFunction(); class CTest { public: CTest(); ~CTest(); }; } ctest.cpp: #include "ctest.h" using namespace Test; // int FreeFunction() -> undefined reference error int Test::FreeFunction() -> works just fine { return 0; } CTest::CTest() -> no need to fully qualify name, i.e. Test::CTest {} CTest::~CTest() {} Thanks for your time & help. int FreeFunction(void); is

I'd like to know the difference between def , cdef and cpdef when I declare a function. The difference between def and the others it's more or less clear. And I've also seen that sometimes it's added the return type in the declaration ( cdef void/double/int... name ) and sometimes not. I'd also like to know how to declare a string variable in cython, as I didn't know it, I declared it as object. def declares a function in Python. Since Cython is based on C runtime, it allows you to use cdef and cpdef . cdef declares function in the layer of C language. As you know (or not?) in C language you

template <typename T> class Node {...}; int main { Node* ptr; ptr = new Node<int>; } Will fail to compile I have to to declare the pointer as Node<int>* ptr; Why do I have to specify the type when declaring a pointer I haven't created the class yet, why does the compiler have to know what type it will be pointing to. And is it not possible to create a generic pointer and decide afterwards what type I want to assign it. progician Templating resolves types at compile-time. When you assign the new Node<int> object to it, the pointer must know at compile-time what type exactly it is. Node<int> and

I don't understand what the following code example does and how it does it: #include <stdio.h> int f(); int a = f(); // a exists just to call f int x = 22; int f() { ++x; return 123; // unimportant arbitrary number } int main() { printf("%d\n", x); } When this is ran it prints 23 , which is the intuitive answer. However in C++, global variables are supposed to be initialized in order of definition. That would mean that a should be initialized before x , because it is defined before x . If that was the case, then the function f would have to be called before x was initialized, because the call

What exactly that declaration of method parameter means: def myFunc(param: => Int) = param What is meaning of => in upper definition? Tomasz Nurkiewicz This is so-called pass-by-name . It means you are passing a function that should return Int but is mostly used to implement lazy evaluation of parameters. It is somewhat similar to: def myFunc(param: () => Int) = param Here is an example. Consider an answer function returning some Int value: def answer = { println("answer"); 40 } And two functions, one taking Int and one taking Int by-name : def eagerEval(x: Int) = { println("eager"); x; } def