Top new questions this week:

Difference between string.empty and string[0] == '\0'

Suppose we have a string std::string str; // some value is assigned What is the difference between str.empty() and str[0] == '\0'?

c++ string

asked by Pro Account 42 votes answered by NathanOliver 74 votes

Violating of strict-aliasing in C, even without any casting?

How can *i and u.i print different numbers in this code, even though i is defined as int *i = &u.i;? I can only assuming that I'm triggering UB here, but I can't see how exactly. (ideone demo ...

c strict-aliasing

asked by Aaron McDaid 34 votes answered by Grzegorz Szpetkowski 38 votes

Fast algorithm to write data from a std::vector to a text file

I currently write a set of doubles from a vector to a text file like this: std::ofstream fout; fout.open("vector.txt"); for (l = 0; l < vector.size(); l++) fout << std::setprecision(10) ...

c++ std ofstream

asked by Diego Fernando Pava 29 votes answered by hungptit 12 votes

C / C++ best practices with signed / unsigned ints and function calls

I am asking this question for two different languages: C and C++. What is best practice when calling functions that have an opposite integer sign expectation to what we require in our code? For ...

c++ c

asked by IamIC 28 votes answered by zwol 8 votes

What is the arithmetic mean of an empty sequence?

Disclaimer: No, I didn't find any obvious answer, contrary to what I expected! When looking for code examples wrt. the arithmetic mean, the first several examples I can turn up via Google seem to be ...

c++ algorithm math floating-point nan

asked by Martin Ba 26 votes answered by R.M. 25 votes

Restrict variadic template arguments

Can we restrict variadic template arguments to a certain type? I.e., achieve something like this (not real C++ of course): struct X {}; auto foo(X... args) Here my intention is to have a function ...

c++ templates variadic-templates c++1z c++-faq

asked by bolov 25 votes answered by bolov 31 votes

In C++, why isn't it possible to friend a template class member function using the template type of another class?

In other words, why does this compile fine : template<typename Type> class A{ public: void f(); }; class B{ friend void A<int>::f(); }; template<> void A<int>::f(){ ...

c++ templates friend

asked by user1729422 21 votes answered by Tunichtgut 2 votes

Greatest hits from previous weeks:

How to rename a local Git branch?

I don't want to rename a remote branch, as described in Rename master branch for both local and remote Git repositories. Instead, I want to use the simplest way to rename a local branch, which hasn't ...

git git-branch

asked by Forrest 4263 votes answered by siride 6818 votes

Redirect from an HTML page?

Is it possible to set up a basic HTML page to redirect to another page on load?

html

asked by chobo 899 votes answered by Valerij 1384 votes

Can you answer these?

Proguard removes Anonymous class in Anonymous class in Java

I have a issue that Proguard is not working when you declare a anonymous class within a anonymous class. This is what it looks like in a basic example: public class Class1 { public void function1 ...

java android proguard anonymous-class

asked by Arne Fischer 7 votes

Grove Pi+ CO2 MH-Z16 sensor

I am using a Raspberry Pi 3 B model with a Grove Pi+ (1.2.2 firmware), and Raspbian for Robots Image. I have plugged in the CO2 MH-Z16 sensor in RPISER port, and I am trying to execute the code that ...

raspberry-pi raspbian grovepi+

asked by Aitul 4 votes

Private member access in template substitution and SFINAE

class A { int a; }; template<typename, typename = void> class test {}; template<typename T> class test<T,decltype(T::a)> {}; int main() { test<A> a; } The code above ...

c++ templates gcc clang sfinae

asked by Eichhörnchen 12 votes