27. Square with Macro and Inline Function

#include <iostream>
using namespace std;

#define SQUARE(x) (x*x)

inline int square(int x) {
    return x * x;
}

int main() {
    int n;
    cin >> n;

    int a = n;
    int b = n;

    cout << "Macro Square: " << SQUARE(++a) << "\n";
    cout << "Inline Square: " << square(++b) << "\n";

    return 0;
}

Solution Details

• SQUARE(++a) expands to (++a * ++a) → a is incremented twice.
• square(++b) increments b once, then calculates safely.
   

👉 Layman’s explanation:

• Macro is like pasting the formula (++a * ++a) directly → a gets bumped twice.
• Inline function is like a calculator: it first takes the incremented number, then squares it.
   

Significance for Embedded Developers

• Using macros in embedded code for sensor values, register fields, or calculations can cause subtle bugs when the same variable is evaluated more than once.
   
• Inline functions solve this problem with the same efficiency.