C program without main function

Hi friends hope you are all fine. 

All of you have must read my previous article on How to print something without using a semicolon in C. This time i have come up with some thing more crazier. What about a program in C without using a main function  

Is it possible to do that ? 

The ans is simply no.

C does't allow us to write a program without using a main function.

Here is the source code

#include <stdio.h>

#define decode(s,t,u,m,p,e,d) m##s##u##t

#define ravish decode(a,n,i,m,a,t,e)

void ravish()

{

printf("stupid, we can do anything ");

}

This program will work perfectly without main function. But the million dollar question is whats the logic behind this . As i said earlier no C program will run without a main function. In above case we have just tricked the compiler to assume that ravish = main .

Here we are using preprocessor directive( A Preprocessor is program which processess the source code before compilation ) #define with arguments to give an impression that the program runs without main. But in reality it runs with a hidden main function.

The ‘##‘ operator is called the token pasting or token merging operator. That is we can merge two or more characters with it.

Look at the 2nd line of code :

#define decode(s,t,u,m,p,e,d) m##s##u##t

The macro decode(s,t,u,m,p,e,d) is being expanded as “msut” (The ## operator merges m,s,u & t into msut). The logic is when you pass (s,t,u,m,p,e,d) as argument it merges the 4th,1st,3rd & the 2nd characters(tokens).

Now look at the third line of code :

#define ravish decode(a,n,i,m,a,t,e)

Here the preprosser replaces the macros "ravish" with the expansion decode(a,n,i,m,a,t,e) .

According to the macro definition in the previous line the argument must be expanded so that the 4th,1st,3rd & the 2nd characters must be merged. In the argument (a,n,i,m,a,t,e) 4th,1st,3rd & the 2nd characters are ‘m’,'a’,'i’ & ‘n’.

So now the next line of code void ravish is replaced by void main before it can be passed to the compiler.

Moral of this article is there never exist a program in c without a main function here we are just playing a gimmick that make people believe that the program runs without a main function .