There may be, yes, if you call the member function via a pointer or reference and the compiler can’t determine with absolute certainty what type of object that pointer or reference points or refers to. For example, consider: void f(B* p) { p->foo(); } void g() { D bar; f(&bar); } Assuming the call to … Read more
As for the question as asked: It depends on the implementation. With MSVC 7.1 this: std:: cout << sizeof(std::vector<int>) << std::endl; gives me 16 (bytes). (3 pointers: begin, end, and end of capacity, plus an allocator) However it should be noted that the pointer-to-vector gives it a larger overhead: in both time and space in … Read more
This really depends on the nature of the binary data, and the constraints that “text” places on your output. First off, if your binary data is not compressed, try compressing before encoding. We can then assume that the distribution of 1/0 or individual bytes is more or less random. Now: why do you need text? … Read more
I wouldn’t worry about it. If you look at the interface of std::array<T, N>, it is very small and most member functions (basically providing wrappers for pointer manipulation) are one-liners that will be completely optimized away / inlined by any decent compiler on Release mode optimization levels. Furthermore, you don’t pay for what you don’t … Read more
Just my 2 cents… I consult exclusively on embedded systems, most of them hard real-time and/or safety/life critical. Most of them run in 256K of flash/ROM or less – in other words, these are not “PC-like” VME bus systems with 1GB+ of RAM/flash and a 1GHz+ CPU. They are deeply embedded, somewhat resource-constrained systems. I … Read more
Here’s a slightly neater (IMO) short but complete program to demonstrate the same thing: using System; class Test { const int Size = 100000; static void Main() { object[] array = new object[Size]; long initialMemory = GC.GetTotalMemory(true); for (int i = 0; i < Size; i++) { array[i] = new string[0]; } long finalMemory = … Read more
One way to examine this is to look at the code in WinDbg. So given the code below, let’s see how that appears on the heap. var numbers = new Int32[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }; The first thing to do is to locate the instance. As I … Read more
Personally I’d go with the option of not using placement new on the array and instead use placement new on each item in the array individually. For example: int main(int argc, char* argv[]) { const int NUMELEMENTS=20; char *pBuffer = new char[NUMELEMENTS*sizeof(A)]; A *pA = (A*)pBuffer; for(int i = 0; i < NUMELEMENTS; ++i) { … Read more
The answer marked correct on this page is actually not correct. That is not a valid way to write a benchmark because of JVM dead code elimination (DCE), on-stack replacement (OSR), loop unrolling, etc. Only a framework like Oracle’s JMH micro-benchmarking framework can measure something like that properly. Read this post if you have any … Read more
I know you’re asking about performance overhead, but you really should not use try/catch and if interchangeably. try/catch is for things that go wrong that are outside of your control and not in the normal program flow. For example, trying to write to a file and the file system is full? That situation should typically … Read more