Variadic template class to add numbers recursively during compilation

The idea of having a class to add numbers (variable parameters) during compilation time recursively. Also wanted to restrict types to a single type while sending parameters to class member function. That said, if we mix int, float and double types to add function shall result in compilation error. How do we achieve this.

The below is the code which actually helps to achieve this:

<code>

#include <fmt/format.h>

template<typename T>
class MyVarSumClass{
    private:
        T _sum = 0;
    public:
        template<typename... TRest>
        T add(T num, TRest... nums){
            static_assert(std::conjunction<std::is_same<TRest, T>...>{}); /* Assert fails 
            if types are different */
            _sum += num;
            return add(nums...); // Next parameter packs gets picked recursively
        }

        // Base case
        T add(T num){
            _sum += num;
            return _sum;
        }
};

int main() 
{
    MyVarSumClass<float> objAdd;
    fmt::print("{}\n", objAdd.add(1.1f,1.2f,1.3f,1.4f,1.5f));
    return 0;
}

</code>

Check here

Comments

Reversing char array without splitting the array to tokens

I was reading about strdup, a C++ function and suddenly an idea came to my mind if this can be leveraged to aid in reversing a character array without splitting the array into words and reconstructing it again by placing spaces and removing trailing spaces. Again, I wanted an array to be passed as a function argument and an array size to be passed implicitly with the array to the function. Assumed, a well-formed char array has been passed into the function. No malformed array checking is done inside the function. So, the function signature and definition are like below: Below is the call from the client code to reverse the array without splitting tokens and reconstructing it. Finally, copy the reversed array to the destination. For GNU C++, we should use strdup instead _strdup . On run, we get the following output: Demo code

A simple approach to generate Fibonacci series via multi-threading

T his is a very simple approach taken to generate the Fibonacci series through multithreading. Here instead of a function, used a function object. The code is very simple and self-explanatory. #include <iostream> #include <mutex> #include <thread> class Fib { public: Fib() : _num0(1), _num1(1) {} unsigned long operator()(); private: unsigned long _num0, _num1; std::mutex mu; }; unsigned long Fib::operator()() { mu.lock(); // critical section, exclusive access to the below code by locking the mutex unsigned long temp = _num0; _num0 = _num1; _num1 = temp + _num0; mu.unlock(); return temp; } int main() { Fib f; int i = 0; unsigned long res = 0, res2= 0, res3 = 0; std::cout << "Fibonacci series: "; while (i <= 15) { std::thread t1([&] { res = f(); }); // Capturing result to respective variable via lambda std::thread t2([&] { res2 = f(); }); std::thread t3(

Close a Window Application from another application.

This is just a demo application code to show how the WM_CLOSE message can be sent to the target process which has a titled window to close the application. To achieve this, either we can use SendMessage or PostMessage APIs to send required Windows messages to the target application. Though both the APIs are dispatching WM_XXXXX message to target application two APIs has some differences, these are as below: 1. SendMessage () call is a blocking call but PostMessage is a non-blocking call(Asynchronous) 2. SendMessage() APIs return type is LRESULT (LONG_PTR) but PostMessage() APIs return type is BOOL(typedef int). In Short, SendMessage () APIs return type depends on what message has been sent to the Windowed target process. For the other one, it's always a non-zero value, which indicates the message has been successfully placed on the target process message queue. Now let's see how can I close a target windowed application "Solitaire & Casual Games" from my custom-

Notebook

Search This Blog