when we have to use for loop in c++ code example

Example 1: c++ for loop

//'i' can be any number
//Can be any comparison operater 
//can be any number compared
//can be any mathmatic operater

for (int i = 0; i<100; i++){
//Do thing
}

//more info on operaters
//https://www.w3schools.com/cpp/cpp_operators.asp

Example 2: c++ for loops

#include <iostream>
#define FOR(i,a) for (int i = 0; i < a; i++)

FOR(i, 3) cout << i << endl;