Category "c++11"

How does #include <bits/stdc++.h> work in C++? [duplicate]

I have read from a codeforces blog that if we add #include <bits/stdc++.h> in a C++ program then there is no need to include any other h

Algorithm to convert std::stack to std::string in C++ STL

In below C++ program I'm deleting a previous character considering '#' as a backspace character. I have used stack to build the string. Is there any C++ STL alg

‘is_trivially_copyable’ is not a member of ‘std’

My gcc version is 4.8.3 20140624. I can use is_pod, is_trivial, is_standard_layout, but fail when trying is_trivially_copyable, is_constructible and is_default_

Why the boost msm calls the guard twice?

I'm implementing a state machine as the following diagram state machine diagram I trigger "event1" and "event2" to the state machine, when "event1" triggered,

How to initialize `std::function` with a member-function?

I am trying to learn std::function and here's my code: #include <iostream> #include <functional> struct Foo { void print_add(int i){ st

error: call to implicitly-deleted copy constructor of 'std::__1::unique_ptr<A, std::__1::default_delete<A> >'

I'm constructing an object that takes a std::vector<std::unique_ptr<A> > as an argument. The constructor is defined like this class B { std::ve

Emplace back thread on vector

Why this cause undefined behavior? #include <iostream> #include <thread> #include <vector> std::vector<std::thread> threads(3); void

how to access only element of unordered_set in c++?

For ex, unordered_set<int> s ; s.insert(100); How do I get value 100 from s? From http://www.cplusplus.com/reference/unordered_set/unordered_set/begin

What is the purpose of std::function, and how to use it?

It is necessary to me to use std::function but I don't know what the following syntax means. std::function<void()> f_name = []() { FNAME(); }; What is

How to run multiple threads in C++ code

I'm a beginner for c++. I wrote a program to extract data from one DB and store those data to another DB. I just want to add multiple threads to speed up the pr

Does auto deduce the type at compile time or runtime in C++ 11?

Consider the following auto a = 10; When does the compiler know that a is an int, at compile time or at run-time? If it deduces the type at run-time, will it n

Check if a given ostream object has been written to

Can I query an ostream object about whether or not it has been written to? For an ostringstream, one could use if(!myOssObject.str().empty()) What about the

Has the C++ standard committee considered templated namespaces?

Namespaces are in many was like classes with no constructors, no destructors, no inheritance, final, and only static methods and members. After all, this kind o

Can't use enum class as unordered_map key

I have a class containing an enum class. class Shader { public: enum class Type { Vertex = GL_VERTEX_SHADER, Geometry = GL_GEOMETRY_SHADE

Sum function with return type large enough to hold result

It's a question from C++ Primer Chapter 16.2.3 (question 16.41): Write a version of sum with a return type that is guaranteed to be large enough to hold t

is there a way to pass nested initializer lists in C++11 to construct a 2D matrix?

Imagine you have a simple matrix class template <typename T = double> class Matrix { T* data; size_t row, col; public: Matrix(size_t m, size_t n

When to use std::launch::deferred?

Lines from Anthony William book: std::launch::deferred indicates that the function call is to be deferred until either wait() or get() is called on the fu

What's the difference between constexpr and const?

What's the difference between constexpr and const? When can I use only one of them? When can I use both and how should I choose one?

const vs constexpr on variables

Is there a difference between the following definitions? const double PI = 3.141592653589793; constexpr double PI = 3.141592653589793; If not, which styl

initialize a vector to zeros C++/C++11

I know in C++11 they added the feature to initialize a variable to zero as such double number = {}; // number = 0 int data{}; // data = 0 Is there a simila