The other likely size for it is that of int, being the “efficient” integer type for the platform. On architectures where it makes any difference whether the implementation chooses 1 or sizeof(int) there could be a trade-off between size (but if you’re happy to waste 7 bits per bool, why shouldn’t you be happy to … Read more
That’s just the way the implicit copy constructor is defined (it wouldn’t make sense calling the default). As soon as you define any constructor (copy or otherwise) its normal automatic behavior is to call the default parent constructor, so it would be inconsistent to change that for one specific user-defined constructor.
Function style casts bring consistency to primitive and user defined types. This is very useful when defining templates. For example, take this very silly example: template<typename T, typename U> T silly_cast(U const &u) { return T(u); } My silly_cast function will work for primitive types, because it’s a function-style cast. It will also work for … Read more
using directives and include preprocessor directives are two different things. The include roughly corresponds to the CLASSPATH environment variable of Java, or the -cp option of the java virtual machine. What it does is making the types known to the compiler. Just including <string> for example will make you able to refer to std::string : … Read more
AFAIK that’s changed in C++0x. I guess it was just an oversight (considering that you can always get the partial specialization effect with more verbose code, by placing the function as a static member of a class). You might look up the relevant DR (Defect Report), if there is one. EDIT: checking this, I find … Read more
To re-iterate, type-punning through unions is perfectly fine in C (but not in C++). In contrast, using pointer casts to do so violates C99 strict aliasing and is problematic because different types may have different alignment requirements and you could raise a SIGBUS if you do it wrong. With unions, this is never a problem. … Read more
The definition of an inline function doesn’t have to be in a header file but, because of the one definition rule (ODR) for inline functions, an identical definition for the function must exist in every translation unit that uses it. The easiest way to achieve this is by putting the definition in a header file. … Read more
It makes sense to give default template arguments. For example you could create a sort function: template<typename Iterator, typename Comp = std::less< typename std::iterator_traits<Iterator>::value_type> > void sort(Iterator beg, Iterator end, Comp c = Comp()) { … } C++0x introduces them to C++. See this defect report by Bjarne Stroustrup: Default Template Arguments for Function Templates … Read more
To expand on Ignacio’s answer: def counter(): count = 0 def c(): nonlocal count count += 1 return count return c x = counter() print([x(),x(),x()]) gives [1,2,3] in Python 3; invocations of counter() give independent counters. Other solutions – especially using itertools/yield are more idiomatic.
I had no idea, so I googled to find something about this. This is what I found. First, it was included as a reserved keyword. Q: What was the entry keyword mentioned in K&R1? A: It was reserved to allow functions with multiple, differently-named entry points, but it has been withdrawn. (From http://archives.devshed.com/forums/c-c-134/c-programming-faqs-371017.html.) It was … Read more