Difference Between X++ and ++X in Java

Many programmers face issues while understanding the difference between x++ and ++x in Java. So, we are going to briefly the difference between these two expressions.

Prefix vs Postfix

Prefix = ++x

Postfix = x++

Both are used to increment value by one but in different manners. If the variable starts with ++, then it is called pre-increment. If it comes after the variable, then it is called the post-increment operator.

Process to Increment in Java

In the post-increment method, we first use the current value and then increase the value by 1.

In the pre-increment method, the value is first incremented by 1 and then used in the Java statement.

Example

int x = 3;
int a = x++;    // a = 3, x = 4
int b = ++a     // b = 4, a = 4

In the first line, the x value is 3, which users assign. In second-line x post-increment method is used to give value to a. So, the first 3 is assigned to a and then incremented by 1, and the x value becomes 4. In the third line, b is assigned with a pre-increment value of a. It will increment a value by 1 and increase a value from 3 to 4. So, both a and b value becomes 4.

Java example:

import java.io.*;

class ABC {
    public static void main(String[] args)
    {
        // initialize i
        int i = 0;
        System.out.println("Post Increment");

        System.out.println(i++);

        int j = 0;
        System.out.println("Pre Increment");

        System.out.println(++j);
    }
}

Output:

Post Increment
0
Pre Increment
1
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