error LNK2005: _main already defined

Question

I recently installed VC++ 2005 EXP edition.

1) I created a project name Radius and created two new items hello.cpp and area.cpp.

2) area.cpp is the first item and hello.cpp is the second one.

3) When I build the project Radius, I got the error

LNK2005: _main already defined in area.obj

Can you guide me to fix the compilation error.

Thanks GKW82

Answer 1

This error is because of multiple definitions of main. You must have defined main in area.cpp as well as in hello.cpp. In C/C++ programs, you can write only one main per application.

Remove one definition of main and it should work fine.

Cheers

Answer 2

Yes. I defined main() in both. I removed the main from hello and I am now getting the error

hello.cpp(4) : error C2447: '{' : missing function header (old-style formal list?)

GKW82

Answer 3

Delete area.cpp and creat it.

Do the thing above.

Answer 4

Nope.. didn't work. Getting the same error.

GKW82

Answer 5

Pls. paste the hello.cpp code

Answer 6

This is what MSDN says :

Error Message

'{' : missing function header (old-style formal list?)

An open brace occurs at global scope without a corresponding function header.

This error can be caused by an old-style C-language formal list.

The following sample generates C2447:

int c;
{}       // C2447

Check whether you are writing the open brace without the function name.

Else post the code.

Answer 7

Here is the piece of code.

1) radius.cpp

#include <iostream>

/* program to calculate radius of a circle */

void main()

{

float area, radius;

printf("Radius = ? ");

scanf("%f", &radius);

area = 3.14159 * radius * radius;

printf("Area = %f", area);

}

2) hell.cpp

include <iostream>

{

printf("Hello world\n");

}

c:\documents and settings\owner\my documents\visual studio 2005\projects\radius\radius\hello.cpp(4) : error C2447: '{' : missing function header (old-style formal list?)

GKW82

Answer 8

Try the following....

1) radius.cpp

#include <iostream>

/* program to calculate radius of a circle */

void main()

{

   float area, radius;

   printf("Radius = ? ");

   scanf("%f", &radius);

   area = 3.14159 * radius * radius;

   printf("Area = %f", area);

}

2) hell.cpp

include <iostream>

void function_name()  // <---------------------------- did you miss this out?

{

   printf("Hello world\n");

}

Answer 9

The whole problem starts when I include the function main() in the hello.cpp. I end up in getting the message

error LNK2005: _main already defined in hello.obj

GKW82.

 

 

Answer 10

I think what you are trying to do is....

---

1.) File: hello.cpp

#include <IOSTREAM>
#include <RADIUS.H>

int main(int argc, char *argv[])
{
      float area = get_area(5);
      printf("Area of circle with radius %d = %f\n", 5, area);
}

2.) File: radius.h

float get_area(float radius);
float get_circumference(float radius);

3.) File: radius.cpp

#include <RADIUS.H>

float get_area(float radius)
{
     return (3.14159 * radius * radius);
}

float get_circumference(float radius)
{
     return (3.14159 * (radius * 2));
}