Hello world with only return in main

Question

What is the way to write a program meeting following requirements:

Has empty main (just returning 0) i.e.

int main(int argc, char** argv) {
    return 0;
}

http://stackoverflow.com/questions/10897552/call-a-function-before-main?lq=1 — chris, Oct 09 '13 at 13:37
Welcome to SO. The idea is that you try to solve this yourself, and when you encounter a specific problem, you ask a question, showing relevant code. — juanchopanza, Oct 09 '13 at 13:38
Googling "Hello World" C gave me 37,000,000 hits. Were they all useless? — Bathsheba, Oct 09 '13 at 13:38
You might want to clarify the requirement that you print the text without any code in main, as many will not spot that. — Neil Kirk, Oct 09 '13 at 13:41
@NeilKirk so I did. I guess, I'll just accept what seems best answer and be more constructive next time. — user2862943, Oct 09 '13 at 13:46
@Bathsheba: It might take quite a while to read through 37,000,000 examples to discover whether any of them have an empty `main`. — Mike Seymour, Oct 09 '13 at 13:52

sukhmel · Accepted Answer · 2013-10-09T14:08:01.640

14

You can do this in different ways. Consider you have #include <iostream> then following methods should be placed before main.

You may use macros, but the result is undefined as noticed in comments. So even if this is an easy way, it should never be used. I will still leave it here for completeness.
```
#define return std::cout << "Hello world!"; return
```

You may use static variable:

int helloWorld() 
{ 
    std::cout << "Hello World"; 
    return 0; 
}
static int print = helloWorld();

... or even simpler:

bool printed = std::cout << "Hello World";

You can do same with object:

struct hello
{
    public:
        hello()
        {
            std::cout << "Hello, world!";
        }
} world;

edited Oct 09 '13 at 14:08

answered Oct 09 '13 at 13:39

sukhmel

2

Note that the behavior of option 1 is undefined. – Pete Becker Oct 09 '13 at 13:58
@PeteBecker, good point, will update. – sukhmel Oct 09 '13 at 14:04

score 1 · Answer 2 · answered Oct 09 '13 at 13:39

1

struct Bob
{
    Bob()
    {
        printf("Hello world!");
    }
} bob;

int main()
{
}

answered Oct 09 '13 at 13:39

Neil Kirk

score 0 · Answer 3 · answered Oct 09 '13 at 13:40

0

Object Instantiation:

struct S
{
    S() { std::cout << "Hello World!"; }
} s;

int main() { }

Or in an expression:

int i = ((std::cout << "Hello World\n"), 5);

int main() { }

answered Oct 09 '13 at 13:40

David G

3 Answers3