arrow functions c++ code example

Example 1: lambda c++

#include <iostream>
#include <string>
 
// returns a lambda
auto makeWalrus(const std::string& name)
{
  // Capture name by reference and return the lambda.
  return [&]() {
    std::cout << "I am a walrus, my name is " << name << '\n'; // Undefined behavior
  };
}
 
int main()
{
  // Create a new walrus whose name is Roofus.
  // sayName is the lambda returned by makeWalrus.
  auto sayName{ makeWalrus("Roofus") };
 
  // Call the lambda function that makeWalrus returned.
  sayName();
 
  return 0;
}

Example 2: arrow operator c++

/* 
 the arrow operator is used for accessing members (fields or methods)
 of a class or struct
 
 it dereferences the type, and then performs an element selection (dot) operation
*/

#include <iostream>
using std::cout;

class Entity {
public:
	const char* name = nullptr;
private:
	int x, y;
public:
	Entity(int x, int y, const char* name)
		: x(x), y(y), name(name) {
		printEntityPosition(this); // "this" just means a pointer to the current Entity
	}

	int getX() { return x; }
	int getY() { return y; }

	friend void printEntityPosition(Entity* e);

};

// accessing methods using arrow
void printEntityPosition(Entity* e) {
	cout << "Position: " << e->getX() << ", " << e->getY() << "\n";
}

int main() {
	/* ----- ARROW ----- */

	Entity* pointer = new Entity(1, 1, "Fred");
	//printEntityPosition(pointer); redacted for redundancy (say that 5 times fast)
	
  	cout << (*pointer).name << "\n"; // behind the scenes
	cout << pointer->name << "\n"; // print the name (with an arrow)

	/* ----- NOT ARROW ----- */

	Entity not_a_pointer(2, 2, "Derf");
	//printEntityPosition(&not_a_pointer); & to convert to pointer

	cout << not_a_pointer.name << "\n"; // print the name (with a dot)

	/* ----- LITERALLY NEITHER ----- */

	std::cin.get(); // wait for input
	return 0; // exit program
}