I’d consider it quite safe to assume that std::string allocates its storage contiguously. At the present time, all known implementations of std::string allocate space contiguously. Moreover, the current draft of C++ 0x (N3000) [Edit: Warning, direct link to large PDF] requires that the space be allocated contiguously (§21.4.1/5): The char-like objects in a basic_string object … Read more
The answer given by Alexey Malistov can be used on MSVC with a minor modification: namespace { template<class T, int discriminator> struct is_complete { static T & getT(); static char (& pass(T))[2]; static char pass(…); static const bool value = sizeof(pass(getT()))==2; }; } #define IS_COMPLETE(X) is_complete<X,__COUNTER__>::value Unfortunately, the __COUNTER__ predefined macro is not part of … Read more
tl;dr: The sequence of the modifications and reads performed in (i+=10)+=10 is well defined in both C++98 and C++11, however in C++98 this is not sufficient to make the behavior defined. In C++98 multiple modifications to the same object without an intervening sequence-point results in undefined behavior, even when the order of those modifications is … Read more
In terms of evaluation sequence, it is easier to think of x*f(x) as if it was: operator*(x, f(x)); so that there are no mathematical preconceptions on how multiplication is supposed to work. As @dan04 helpfully pointed out, the standard says: Section 1.9.15: “Except where noted, evaluations of operands of individual operators and of subexpressions of … Read more
The C++ memory model is the specification of when and why physical memory is read/written with respect to C++ code. Until the next C++ standard, the C++ memory model is the same as C. In the C++0x standard, a proper memory model for multithreading is expected to be included (see here), and it will be … Read more
I had the same problem. For C89 the following is true: With C89-style initializers, structure members must be initialized in the order declared, and only the first member of a union can be initialized I found this explanation at: Initialization of structures and unions
In C++ the macros are not automatically defined just by including the file. You need to add the following: #define __STDC_FORMAT_MACROS 1 before #include <inttypes.h> How to printf uint64_t? Fails with: “spurious trailing ‘%’ in format”
A std::string’s allocation is not guaranteed to be contiguous under the C++98/03 standard, but C++11 forces it to be. In practice, neither I nor Herb Sutter know of an implementation that does not use contiguous storage. Notice that the &s[0] thing is always guaranteed to work by the C++11 standard, even in the 0-length string … Read more
I’m currently playing around with the Boost.Enum proposal from the Boost Vault (filename enum_rev4.6.zip). Although it was never officially submitted for inclusion into Boost, it’s useable as-is. (Documentation is lacking but is made up for by clear source code and good tests.) Boost.Enum lets you declare an enum like this: BOOST_ENUM_VALUES(Level, const char*, (Abort)(“unrecoverable problem”) … Read more
Found in the documentation for the 1984-5 release of CFront, the first C++ compiler: The constructor can be written like this: vec.vec(int lb, int hb) : (hb-lb+1) { if (hb-lb<0) hb = lb; low = lb; high = hb; } The construct : (hb-lb+1) is used to specify the argument list needed for the base … Read more