Two 'main' functions in C/C++

Question

Can I write a program in C or in C++ with two main functions?

Answer 1

This might be the answer for your query

void main()
{
    func1();
}
#define main func1
void main()
{
    printf("inside 2nd main");
}

Answer 2

No. All programs have a single main(), that's how the compiler and linker generate an executable that start somewhere sensible.

You basically have two options:

1. Have the main() interpret some command line arguments to decide what actual main to call. The drawback is that you are going to have an executable with both programs.

2. Create a library out of the shared code and compile each main file against that library. You'll end up with two executables.

Answer 3

You can have two functions called main. The name is not special in any way and it's not reserved. What's special is the function, and it happens to have that name. The function is global. So if you write a main function in some other namespace, you will have a second main function.

namespace kuppusamy {
  int main() { return 0; } 
}

int main() { kuppusamy::main(); }

The first main function is not special - notice how you have to return explicitly.

Answer 4

No, main() defines the entry point to your program and you must only one main() function(entry point) in your program.

Frankly speaking your question doesn't make much sense to me.

Answer 5

What do you mean by "main function"? If you mean the first function to execute when the program starts, then you can have only one. (You can only have one first!)

If you want to have your application do different things on start up, you can write a main function which reads the command line (for example) and then decides which other function to call.

Answer 6

Standard C doesn’t allow nested functions but GCC allows them.

void main()

{

void main()

{

printf(“stackoverflow”);

}

printf(“hii”);

}

The o/p for this code will be -hii

if you use GCC compiler.

There is a simple trick if you want to use 2 main() in your program such that both are successfully executed;you can use define.Example-

void main()

{

printf("In 1st main\n");

func1();

}

#define main func1

void main()

{

printf("In 2nd main\n");

}

Here the o/p will be:

In 1st main

In 2nd main

NOTE:here warning conflicting types of func1 will be generated.

And yes don’t change the place of define.