Read it backwards (as driven by Clockwise/Spiral Rule): int* – pointer to int int const * – pointer to const int int * const – const pointer to int int const * const – const pointer to const int Now the first const can be on either side of the type so: const int * … Read more
PDF versions of the standard As of 1st September 2014 March 2022, the best locations by price for the official C and C++ standards documents in PDF seem to be: C++20 – ISO/IEC 14882:2020: 212 CAD (about $165 US) from csagroup.org C++17 – ISO/IEC 14882:2017: $90 NZD (about $65 US) from Standards New Zealand C++14 … Read more
The problem C++ includes useful generic functions like std::for_each and std::transform, which can be very handy. Unfortunately they can also be quite cumbersome to use, particularly if the functor you would like to apply is unique to the particular function. #include <algorithm> #include <vector> namespace { struct f { void operator()(int) { // do something … Read more
A declaration introduces an identifier and describes its type, be it a type, object, or function. A declaration is what the compiler needs to accept references to that identifier. These are declarations: extern int bar; extern int g(int, int); double f(int, double); // extern can be omitted for function declarations class foo; // no extern … Read more
C++03 (Source: Iterator Invalidation Rules (C++03)) Insertion Sequence containers vector: all iterators and references before the point of insertion are unaffected, unless the new container size is greater than the previous capacity (in which case all iterators and references are invalidated) [23.2.4.3/1] deque: all iterators and references are invalidated, unless the inserted member is at … Read more
Arrays on the type level An array type is denoted as T[n] where T is the element type and n is a positive size, the number of elements in the array. The array type is a product type of the element type and the size. If one or both of those ingredients differ, you get … Read more
Foo(int num): bar(num) This construct is called a Member Initializer List in C++. Simply said, it initializes your member bar to a value num. What is the difference between Initializing and Assignment inside a constructor? Member Initialization: Foo(int num): bar(num) {}; Member Assignment: Foo(int num) { bar = num; } There is a significant difference … Read more
This is because of padding added to satisfy alignment constraints. Data structure alignment impacts both performance and correctness of programs: Mis-aligned access might be a hard error (often SIGBUS). Mis-aligned access might be a soft error. Either corrected in hardware, for a modest performance-degradation. Or corrected by emulation in software, for a severe performance-degradation. In … Read more
The way to think about this is to “think like a compiler”. Imagine you are writing a compiler. And you see code like this. // file: A.h class A { B _b; }; // file: B.h class B { A _a; }; // file main.cc #include “A.h” #include “B.h” int main(…) { A a; } … Read more
Introduction For a technical overview – skip to this answer. For common cases where copy elision occurs – skip to this answer. Copy elision is an optimization implemented by most compilers to prevent extra (potentially expensive) copies in certain situations. It makes returning by value or pass-by-value feasible in practice (restrictions apply). It’s the only … Read more