Yes, it's possible! In this text I will show a set of tricks to do it. I will present this on a simple program that that reads two numbers from STDIN and prints theirs sum to the STDOUT.
Normally I would start this program from declaring two variables:
int a, b;
Unfortunately, there's a semicolon at the end of the line. It can be omitted by using variables already declared for the main function:
int main(int argc, char* argv[])
I will use argc as a and argv[0] as b. Normally, next thing would be reading two values from STDIN and placing them in a and b variables. It could be like this:
scanf("%d%d", &a, &b);
Once again, there's a semicolon! This one can be skipped by using 'if' statement:
if (scanf("%d%d", &a, &b)) {}
The same trick can be used for printing to STDOUT:
if( printf("%d", a + b ) ){}
Above code compiles and works correctly, but normally the main function should return zero if everything went OK:
return 0;
This semicolon can't be avoided by using the trick with 'if' statement, but we other construction can help here:
if(brk(0)){}
That's all, below is full source code:
#include <stdio.h>
#include <unistd.h>
int main(int argc, char* argv[]) {
if (scanf("%d%d", &argc, &argv[0])) {}
if (printf("%d", argc+argv[0])) {}
if (brk(0)) {}
}
Leave a comment, if you know other interesting riddles or tricks that can be used here!