How can I write c++ main function?

Question

can I write c++ main function without return integer value? I am using visual studio 2010.

#include <iostream>
using namespace std;

int main()
{
    cout <<"In main function" << endl;  
    //return 0; 
}    `

Are you getting any errors or warnings with this code? – πάντα ῥεῖ Apr 30 '15 at 17:52 — πάντα ῥεῖ, Apr 30 '15 at 17:52
No. I didn't get any errors or warnings. – Sharthrak Niroshan Apr 30 '15 at 17:55 — Sharthrak Niroshan, Apr 30 '15 at 17:55

Arun A S · Answer 1 · 2015-04-30T18:03:22.087

4

Yes, since the release of C99, you can skip the return value of main().

Let's look at C++11

3.6.1

A return statement in main has the effect of leaving the main function (destroying any objects with automatic storage duration) and calling std::exit with the return value as the argument. If control reaches the end of main without encountering a return statement, the effect is that of executing
return 0;

edited Apr 30 '15 at 18:03

answered Apr 30 '15 at 17:50

Arun A S

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What does C99 have to do with C++? – Mike Seymour Apr 30 '15 at 18:18
@MikeSeymour I meant all compilers after succeeding C99 ( whether it be C or C++ ) will put return type as 0, or is that wrong? Please correct me if I was wrong on this part. – Arun A S Apr 30 '15 at 18:20
Can the return value of `main` be casted? For example: `(void) main(void)` – Thomas Matthews Apr 30 '15 at 18:25
@ThomasMatthews, AFAIK, No ( tried compiling as well, and it didn't compile ) – Arun A S Apr 30 '15 at 18:31

score 3 · Answer 2 · answered Apr 30 '15 at 17:55

3

According to the C++ Standard (3.6.1 Main function)

5 A return statement in main has the effect of leaving the main function (destroying any objects with automatic storage duration) and calling std::exit with the return value as the argument. If control reaches the end of main without encountering a return statement, the effect is that of executing
return 0;

Thus the shortest C++ program is

int main() {}

answered Apr 30 '15 at 17:55

Vlad from Moscow

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`int main(){}` is 1 byte shorter ;-) – Aykhan Hagverdili Mar 20 '20 at 12:57

score 1 · Answer 3 · edited Apr 30 '15 at 19:32

1

With the VS2010 compiler, you actually can declare it as void main() if you're not interested in returning a value.

Though this isn't a C++ standard compliant feature.

edited Apr 30 '15 at 19:32

πάντα ῥεῖ

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answered Apr 30 '15 at 17:54

Cristik

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You are wrong. main shall have return type int. – Vlad from Moscow Apr 30 '15 at 17:57
3

The compiler that comes with VS 2010 allows declaring `main` as `void`. – Cristik Apr 30 '15 at 18:02
@Cristik: That is irrelevant. – Lightness Races in Orbit May 05 '15 at 16:36
@LightnessRacesinOrbit: the asker said that he is using VS2010, so I gave an answer that suits that environment, as VS allows you to declare `void` mains, thus the developer doesn't need to type the `return` statement. – Cristik May 05 '15 at 16:37
That you don't need to type the `return` statement is unrelated to this notion that you can change the return _type_. The two are distinct considerations. C++ allows you to omit `return 0`; it does not allow you to change `int` to `void`. I don't really care that some implementation has an extension: the question is clearly asking about C++ (with IDE provided as additional, contextual information). – Lightness Races in Orbit May 05 '15 at 16:47
1

That's your opinion and I respect it, I just wanted to let the asker know that there is a workaround to his `can I write c++ main function without return integer value?` question. Also the good people that edited my answer added a clarification that this is not standard, so I don't think this answer would hurt anyone. That doesn't mean though that people should agree with it :) – Cristik May 05 '15 at 17:20

How can I write c++ main function?

3 Answers3