Example of behavioral change when using `virtual` in C++

greeter.cpp

#include <print>

using namespace std;

class GenericGreeter {
 public:
  void Greet(const char* name) {
    println("Hi {}.", name);
  }
};

class FriendlyGreeter : public GenericGreeter {
 public:
  void Greet(const char* name) {
    println("Hello {}! It's a pleasure to meet you!", name);
  }
};

int main() {
  FriendlyGreeter* friendlyGreeter = new FriendlyGreeter;
  GenericGreeter* genericGreeter = (GenericGreeter*)friendlyGreeter;

  friendlyGreeter->Greet("Bob");
  genericGreeter->Greet("Alice");

  delete friendlyGreeter;

  return 0;
}

Makefile

.PHONY: all
all: build run

CXX := $(or $(CXX),zig c++)

.PHONY: build
build:
	${CXX} -std=c++23 -o greeter greeter.cpp
	${CXX} -std=c++23 -o virtual virtual.cpp

.PHONY: run
run:
	./greeter
	./virtual

.PHONY: clean
clean:
	rm -f ./greeter
	rm -f ./virtual

virtual.cpp

#include <print>

using namespace std;

class GenericGreeter {
 public:
  virtual void Greet(const char* name) {
    println("Hi {}.", name);
  }
};

class FriendlyGreeter : public GenericGreeter {
 public:
  virtual void Greet(const char* name) {
    println("Hello {}! It's a pleasure to meet you!", name);
  }
};

int main() {
  FriendlyGreeter* friendlyGreeter = new FriendlyGreeter;
  GenericGreeter* genericGreeter = (GenericGreeter*)friendlyGreeter;

  friendlyGreeter->Greet("Bob");
  genericGreeter->Greet("Alice");

  delete friendlyGreeter;

  return 0;
}

7c7
<   void Greet(const char* name) {
---
>   virtual void Greet(const char* name) {
14c14
<   void Greet(const char* name) {
---
>   virtual void Greet(const char* name) {