C :: Remove The Functions In A Program By Pre-processing

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);
}
}

[Code]...

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?