alex_k@blackcastle:~/work/1$ more aaa.cpp
int main()
{
    float NULL = 3.14f;
    if (NULL) throw "what?";
    return 0;
}
alex_k@blackcastle:~/work/1$ g++ aaa.cpp
alex_k@blackcastle:~/work/1$ ./a.out
terminate called after throwing an instance of 'char const*'
Aborted (core dumped)
alex_k@blackcastle:~/work/1$ 

	if (NULL) printf("what?");

alex_k@blackcastle:~/work/1$ more test.h
#pragma once

void test();
alex_k@blackcastle:~/work/1$ more test.cpp
#include "test.h"

void test()
{
	auto NULL = 3.14f;
	if (NULL) throw("what?");
}
alex_k@blackcastle:~/work/1$ more main.cpp
#include <iostream>

#include <string>

#include "test.h"

int main()
{
	try {
		test();
	}
	catch (const char* s) {
		std::cerr << s << std::endl;
	}
    return 0;
}
alex_k@blackcastle:~/work/1$ g++ test.cpp main.cpp -std=c++11
alex_k@blackcastle:~/work/1$ ./a.out 
what?
alex_k@blackcastle:~/work/1$