Conditional compilation

Write a program to show conditional compilation using macros.

#include<stdio.h>
#define op 2
int main()
{
	int i = 20,j = 10, k = 0;
	#if(op == 1)
		k = i + j;
	#elif(op == 2)
		k = i - j;
	#elif(op == 3)
		k = i * j;
	#elif(op == 4)
		k = i / j;
	#elif(op == 5)
		k = i % j;
	#else
		printf("Invalid Choice");
	#endif
		printf("%d\n",k);
	return 0;
}

Output

10