Thread: C Preprocessing

Hello
Is there a program that can remove the functions in a program by preprocessing

Code:

#include<stdio.h>
int is_even(int number);
int main(void)
{
	if(is_even(number))
	{
		printf("%d is even", number);
	}
}


int is_even(int number)
{
	return number%2 ==0
}

To something like

Code:

#include<stdio.h>
int is_even(int number);
int main(void)
{
	if( number%2 ==0 )
	{
		printf("%d is even", number);
	}
}

I use the "-E" option when compiling with gcc on linux but its output still contains funcitons. Is there a preprocessing program that can remove functions from a program?
Thanks

So to clarify, you want a program that will go through your source files and delete all function definitions with the exception of main? And it should leave all the prototypes, global and file scope variables, preprocessor directives (#include, #define, etc) alone? I find that a strange request, so if you could explain why you want to do that, perhaps we could suggest a better alternative.

That being said, I don't know of anything that does exactly what you want, but perhaps if you look for some refactoring tools for C (or maybe even C++), you could find one that will do what you want. I personally have never used such tools, so I can't suggest any. Perhaps others can, or perhaps Google will help you.

There might not be something that specifically optimizes out the function in C, but when your compiler generates the machine code, it probably would be optimized out there.

The compiler might see that instead of 2 jumps, it can just relocate that bit of logic. Also if you have code that will generate a numerical output in a deterministic way, you may see your function won't even make it into the machine code and your compiler has hard coded a value in the ultimate program.

Originally Posted by anduril462

So to clarify, you want a program that will go through your source files and delete all function definitions with the exception of main? And it should leave all the prototypes, global and file scope variables, preprocessor directives (#include, #define, etc) alone? I find that a strange request, so if you could explain why you want to do that, perhaps we could suggest a better alternative.

The reason i want such a program is that when reading through a source code, i have having to scroll up and down every time a function is called so i am looking for a program that can go through a source code and instead of putting function calls, it can replace it with the actual function itself

Thanks for the help