Check out example codes for "define in cpp". It will help you in understanding the concepts better.

Code Example 1

#include <iostream> 
  
// macro definition 
#define LIMIT 5 

int main() 
{ 
    for (int i = 0; i < LIMIT; i++) { 
        std::cout << i << "\n"; 
    } 
  
    return 0; 
}

Code Example 2

// The #define preprocessor directive creates symbolic constants
#include <iostream>
using namespace std;

#define CONSTANT 2.71828

int main () {
   cout << "Declared constant: " << CONSTANT << endl; 

   return 0;
}

Learn ReactJs, React Native from akashmittal.com