op3.c

op3.c

//#include <stdio.h>

#define PRINTX printf("%d\n",x)

// ↓int main()↓ 
main()
{
	int x=2, y, z;

	x *= 3 + 2; PRINTX;
	x *= y = z = 4; PRINTX;
	x = y == z; PRINTX;
	x == ( y = z ); PRINTX;
}

bash

/*
op2.c:6:1: warning: return type defaults to ‘int’ [-Wimplicit-int]
    6 | main()
      | ^~~~
op2.c: In function ‘main’:
op2.c:3:16: warning: implicit declaration of function ‘printf’ [-Wimplicit-function-declaration]
    3 | #define PRINTX printf("%d\n",x)
      |                ^~~~~~
op2.c:10:21: note: in expansion of macro ‘PRINTX’
   10 |         x *= 3 + 2; PRINTX;
      |                     ^~~~~~
op2.c:1:1: note: include ‘<stdio.h>’ or provide a declaration of ‘printf’
  +++ |+#include <stdio.h>
    1 | //#include <stdio.h>
op2.c:3:16: warning: incompatible implicit declaration of built-in function ‘printf’ [-Wbuiltin-declaration-mismatch]
    3 | #define PRINTX printf("%d\n",x)
      |                ^~~~~~
op2.c:10:21: note: in expansion of macro ‘PRINTX’
   10 |         x *= 3 + 2; PRINTX;
      |                     ^~~~~~
op2.c:3:16: note: include ‘<stdio.h>’ or provide a declaration of ‘printf’
    3 | #define PRINTX printf("%d\n",x)
      |                ^~~~~~
op2.c:10:21: note: in expansion of macro ‘PRINTX’
   10 |         x *= 3 + 2; PRINTX;
      |                     ^~~~~~
*/