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C++

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C++ is an open source programming language created in 1985 by Bjarne Stroustrup.

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C++ ( pronounced cee plus plus) is a general-purpose programming language. It has imperative, object-oriented and generic programming features, while also providing facilities for low-level memory manipulation. It was designed with a bias toward system programming and embedded, resource-constrained and large systems, with performance, efficiency and flexibility of use as its design highlights. Read more on Wikipedia...


Example from Compiler Explorer:
// Type your code here, or load an example. int square(int num) { return num * num; }
Example from Riju:
#include <iostream> int main() { std::cout << "Hello, world!" << std::endl; return 0; }
Example from hello-world:
#include <iostream> int main() { std::cout << "Hello World" << std::endl; }
// Hello World in C++ (pre-ISO) #include <iostream.h> main() { cout << "Hello World!" << endl; return 0; }
Example from Linguist:
#include <cstdint> namespace Gui { }
Example from Wikipedia:
1 #include <iostream> 2 #include <vector> 3 #include <stdexcept> 4 5 int main() { 6 try { 7 std::vector<int> vec{3, 4, 3, 1}; 8 int i{vec.at(4)}; // Throws an exception, std::out_of_range (indexing for vec is from 0-3 not 1-4) 9 } 10 // An exception handler, catches std::out_of_range, which is thrown by vec.at(4) 11 catch (std::out_of_range &e) { 12 std::cerr << "Accessing a non-existent element: " << e.what() << '\n'; 13 } 14 // To catch any other standard library exceptions (they derive from std::exception) 15 catch (std::exception &e) { 16 std::cerr << "Exception thrown: " << e.what() << '\n'; 17 } 18 // Catch any unrecognised exceptions (i.e. those which don't derive from std::exception) 19 catch (...) { 20 std::cerr << "Some fatal error\n"; 21 } 22 }
#define #defined #elif #else #endif #error #if #ifdef #ifndef #include #line #pragma #undef alignas alignof and and_eq asm atomic_cancel atomic_commit atomic_noexcept auto bitand bitor bool break case catch char char16_t char32_t class compl concept const constexpr const_cast continue decltype default delete do double dynamic_cast else enum explicit export extern false final float for friend goto if inline int import long module mutable namespace new noexcept not not_eq nullptr operator or or_eq override private protected public register reinterpret_cast requires return short signed sizeof static static_assert static_cast struct switch synchronized template this thread_local throw transaction_safe transaction_safe_dynamic true try typedef typeid typename union unsigned using virtual void volatile wchar_t while xor xor_eq

Language features

Feature Supported Token Example
Access Modifiers โœ“
Exceptions โœ“
Classes โœ“
Threads โœ“
Virtual function โœ“
class Animal {
 public:
  // Intentionally not virtual:
  void Move(void) {
    std::cout << "This animal moves in some way" << std::endl;
  }
  virtual void Eat(void) = 0;
};

// The class "Animal" may possess a definition for Eat if desired.
class Llama : public Animal {
 public:
  // The non virtual function Move is inherited but not overridden.
  void Eat(void) override {
    std::cout << "Llamas eat grass!" << std::endl;
  }
};
Templates โœ“
template 
Vector& Vector::operator+=(const Vector& rhs)
{
    for (int i = 0; i < length; ++i)
        value[i] += rhs.value[i];
    return *this;
}
Operator Overloading โœ“
Multiple Inheritance โœ“
Namespaces โœ“
#include 
using namespace std;

// Variable created inside namespace
namespace first
{
  int val = 500;
}
 
// Global variable
int val = 100;
// Ways to do it: https://en.cppreference.com/w/cpp/language/namespace
namespace ns_name { declarations }
inline namespace ns_name { declarations }
namespace { declarations }
ns_name::name
using namespace ns_name;
using ns_name::name;
namespace name = qualified-namespace ;
namespace ns_name::inline(since C++20)(optional) name { declarations }
Function Overloading โœ“
// volume of a cube
int volume(const int s) {
 return s*s*s;
}
// volume of a cylinder
double volume(const double r, const int h) {
  return 3.1415926*r*r*static_cast(h);
}
Iterators โœ“
std::vector items;
items.push_back(5);  // Append integer value '5' to vector 'items'.
items.push_back(2);  // Append integer value '2' to vector 'items'.
items.push_back(9);  // Append integer value '9' to vector 'items'.

for (auto it = items.begin(); it != items.end(); ++it) {  // Iterate through 'items'.
  std::cout << *it;  // And print value of 'items' for current index.
}
Constructors โœ“
class Foobar {
 public:
  Foobar(double r = 1.0,
         double alpha = 0.0)  // Constructor, parameters with default values.
      : x_(r * cos(alpha))    // <- Initializer list
  {
    y_ = r * sin(alpha);  // <- Normal assignment
  }

 private:
  double x_;
  double y_;
};
Foobar a,
       b(3),
       c(5, M_PI/4);
Single Dispatch โœ“
Partial Application โœ“
// http://www.cplusplus.com/reference/functional/bind/
// bind example
#include      // std::cout
#include    // std::bind

// a function: (also works with function object: std::divides my_divide;)
double my_divide (double x, double y) {return x/y;}

struct MyPair {
  double a,b;
  double multiply() {return a*b;}
};

int main () {
  using namespace std::placeholders;    // adds visibility of _1, _2, _3,...

  // binding functions:
  auto fn_five = std::bind (my_divide,10,2);               // returns 10/2
  std::cout << fn_five() << '\n';                          // 5

  auto fn_half = std::bind (my_divide,_1,2);               // returns x/2
  std::cout << fn_half(10) << '\n';                        // 5

  auto fn_invert = std::bind (my_divide,_2,_1);            // returns y/x
  std::cout << fn_invert(10,2) << '\n';                    // 0.2

  auto fn_rounding = std::bind (my_divide,_1,_2);     // returns int(x/y)
  std::cout << fn_rounding(10,3) << '\n';                  // 3

  MyPair ten_two {10,2};

  // binding members:
  auto bound_member_fn = std::bind (&MyPair::multiply,_1); // returns x.multiply()
  std::cout << bound_member_fn(ten_two) << '\n';           // 20

  auto bound_member_data = std::bind (&MyPair::a,ten_two); // returns ten_two.a
  std::cout << bound_member_data() << '\n';                // 10

  return 0;
}
Magic Getters and Setters X

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