Jul 29, 20211 min read

What is difference between i++ and ++i?

++i and i++ both increment the value of i by 1 but in a different way. If ++ precedes the variable, it is called pre-increment operator and it comes after a variable, it is called post-increment operator.

The main difference is the order of operations between the increment of the variable and the value the operator returns. So ++i returns the value after it is incremented, while i++ return the value before it is incremented. At the end, in both cases the i will have its value incremented.

Post-increment i++

i++ is post increment operator, which increment the value of i after execution, and it provides the current value of i first and then increment i.

the original value is loaded into memory, then increment the variable
the value of the expression is the original value

Pre-increment ++i

++i is pre-increment operator. Which increment the value of i during the execution, and it provides the incremented value of i.

increment the variable
the value of the expression is the final value

Example of Post-increment and Pre-increment:

import java.io.*;
  
class GFG {
 public static void main(String[] args)
 {
 // initialize i
 int i = 0;
 System.out.println("Post-Increment");
  
 // i values is incremented to 1 after returning
 // current value i.e; 0
 System.out.println(i++);
  
 // initialized to 0
 int j = 0;
 System.out.println("Pre-Increment");
  
 // j is incremented to 1 and then it's value is
 // returned
 System.out.println(++j);
 }
}

Output: