#define

Question

#include <iostream>
using namespace std;
#define x 5+2
int main() {
int i;
i = x*x*x;
cout << i;
return 0;
}

// output is 27

How does x become 3?
How does #define x 5+2 come into play?

Answer 1

The #define is part of the preprocessor language for C and C++. When they're used in code, the compiler replaces the #define statement with whatever we want.

x is replaced by 5+2 so we have 5+2*5+2*5+2, which the compiler translates to 5+10+10+2, or 27.