### Selection Sort (C++ Way)

Selection Sort using Standard Template Libraries (not C++ 11):

Selection sort works by finding smallest element from the list unsorted list, swap with leftmost element and proceed until all the elements are in order.

Selecting the lowest element requires scanning all n elements (this takes n − 1 comparisons) and then swapping it into the first position. Finding the next lowest element requires scanning the remaining n − 1 elements and so on. Hence the complexity is O(N^2).

The C++ implementation is like below:

#include < iostream >
#include < algorithm >
#include < vector >

template < class ForwardIterator1, class ForwardIterator2 >
void iters_swap (ForwardIterator1 a, ForwardIterator2 b)
{
std::swap (*a, *b);
}

template < typename T >
void selectionSort(T &v)
{
// Selection sort
std::vector::iterator it = v.begin();
while(it != v.end())
{
std::vector::iterator i_Min = std::min_element(it, v.end());
iters_swap(i_Min, it);
++it;
}
}

int main()
{
int arr[] = {34, 20, 99, 10, 23};
std::vector v(std::begin(arr), std::end(arr));

// Before sorting
for (std::vector::const_iterator i = v.begin(); i != v.end(); ++i)
{
std::cout << *i << ' ';
}
std::cout << std::endl;

selectionSort(v);

// After sorting
for (std::vector::const_iterator iSort = v.begin(); iSort != v.end(); ++iSort)
{
std::cout << *iSort << ' ';
}
std::cout << std::endl;
return 0;
}

1. Using std::min_element() to get smallest element from vector.
2. Then swapping with leftmost one as required
3. Continuing till rightmost boundary is reached for vector.

### 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-