using define in c++ code example

Example 1: how to declare a function in c++

// function example
#include <iostream>
using namespace std;

int addition (int a, int b)
{
  int r;
  r=a+b;
  return r;
}

Example 2: define in cpp

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

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

Example 3: #define in cpp

// 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;
}