the basic format or the first executable code line is the
main function in C.... so if we try to print the anything
without main we are trying to modify the basic concepts of C
and this  will not look nice....

thank u

by using the comment lines we can get the output

To display "hello world"
 
 printf("\"hello world\"");

main() method is the entry point for any c/c++ program which
is compiled/linked as executable. C/C++ does not force
anyone to use only main() method as the entry point. This is
only the default behavior and can be changed. This is
generally slightly different for different compiler. But you
can do this.. Simply define any other method say noMe() to
be the entry point for the executable. 
Who the hell uses main()to do main stuffs in any
executable.. It should have been called something like
start() ot begin().. :)

Well this is not the answer.. Just little guidance..

And some deserts for Mr. Vignesh1988i ..
For your kind attention sir.. Method main() is not the first
line in any executable... Have you ever heard of
initialization?? 
Yes you can say what ever the developer writes in any
program starts in main()..

Here is a basic sample which uses main as the entry point.. 
#include <stdio.h>
#define myProxyMain main

int myProxyMain()
{
  printf("\nHello World !!");
  getchar();	
  return 0;
}

Just note that at source level there is no main but once
preprocessing we still have the old main() method.. Which
means we still have the main method in the object module as
well as the executable..

#include<stdio.h>
#include<conio.h>
printf("hello world");

#include<stdio.h>
#define nitish main
void nitish()
{
printf("Hello World");
}

Using Macros we can solve this.

#include<stdio.h>
#include<conio.h>

#define manne main

void manne()
{
 clrscr();
 printf("HELLO WORLD\n");
 getch();
}

its not possible.

Use pragma directive if you want to do something before 
executing main function..

This is the other way you can use it.....

#include<stdio.h>
                                                           
                                                           
    int hello();
                                                           
                                                           
     
_start()
{
        _exit(hello());
}
                                                           
                                                           
     
int hello()
{
        printf("\n \t\t\t\t\tHello World\n");
        printf("\n \t \t \t Welome to C in Linux\n");
}

compile the above file using the following command

# gcc -nostartfiles <filename.c>

# ./a.out

#include<stdio.h>
#include<iostream.h>
class World
{
 public:
 World()
 {
  printf("Hello world");
 }
}

world w1;


Here the object is declared globaly.so when the object is
defined it will call the constructor of that & that will
display the "hello world". no need to write main. as it is
global.

the question is wrong

#include<stdio.h>
#include<conio.h>
#define uttam main
uttam()
{
printf("hello world");
getch();
return 0;
}