Guard statement from Swift in C++

guardStatement.cpp

#include <iostream>
#define guard(_condition) if (bool(_condition)){}

using namespace std;

// Example inside a function
template <typename Type>
Type biggestNumber(Type* numbers, const size_t& size) {
	
	guard(numbers != nullptr) else {
		cerr << "[Error, null pointer found] ";
		return Type{};
	}
	
	Type biggest = 0;
	for (size_t i = 0; i < size; ++i) {
		if (numbers[i] > biggest) {
			biggest = numbers[i];
		}
	}
	
	return biggest;
}

int main() {
	
	boolalpha(cout);
	
	int* i = new int{10}; // nullptr;
	
	guard(i != nullptr) else {
		cerr << "Null pointer" << endl;
		exit(1);
	}
	
	guard(*i == 10) else { cerr << "Incorrect value" << endl; }
	
	delete i;
	
	//
	double* numbers = nullptr; //new double[4]{1.1, 2.3, 9.01, 9.0};
	cout << "Biggest number: " << biggestNumber(numbers, 4) << endl;
	
	delete[] numbers;
}