Below is my (current) favorite demonstration of why parsing C++ is (probably) Turing-complete, since it shows a program which is syntactically correct if and only if a given integer is prime. So I assert that C++ is neither context-free nor context-sensitive. If you allow arbitrary symbol sequences on both sides of any production, you produce … Read more
I understand the situation a bit better now (in no small amount due to the answers here!), so I thought I add a little write-up of my own. There are two distinct, though related, concepts in C++11: Asynchronous computation (a function that is called somewhere else), and concurrent execution (a thread, something that does work … Read more
set print elements 0 From the GDB manual: set print elements number-of-elements Set a limit on how many elements of an array GDB will print. If GDB is printing a large array, it stops printing after it has printed the number of elements set by the set print elements command. This limit also applies to … Read more
The typical way to check for existence in many STL containers such as std::map, std::set, … is: const bool is_in = container.find(element) != container.end();
I don’t think it will make a significant difference in compile time but #pragma once is very well supported across compilers but not actually part of the standard. The preprocessor may be a little faster with it as it is more simple to understand your exact intent. #pragma once is less prone to making mistakes … Read more
Why use pointers over normal variables? Short answer is: Don’t. 😉 Pointers are to be used where you can’t use anything else. It is either because the lack of appropriate functionality, missing data types or for pure perfomance. More below… When and where should I use pointers? Short answer here is: Where you cannot use … Read more
Use reference wherever you can, pointers wherever you must. Avoid pointers until you can’t. The reason is that pointers make things harder to follow/read, less safe and far more dangerous manipulations than any other constructs. So the rule of thumb is to use pointers only if there is no other choice. For example, returning a … Read more
There’s a fairly simple trick to do so, since the spec now guarantees vectors store their elements contiguously: std::vector<double> v; double* a = &v[0];
It won’t automatically convert (thank god). You’ll have to use the method c_str() to get the C string version. std::string str = “string”; const char *cstr = str.c_str(); Note that it returns a const char *; you aren’t allowed to change the C-style string returned by c_str(). If you want to process it you’ll have … 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