How Do Prefix and Postfix Increment/Decrement Operators Differ in Java?

Understanding Prefix and Postfix Increment/Decrement Operators in Java

Operators like (increment) and -- (decrement) can be applied in a prefix or postfix manner. The placement of these operators affects the evaluation and assignment of the variable.

In the provided Java program:

class PrePostDemo {
    public static void main(String[] args) {
        int i = 3;
        i++;

        System.out.println(i);    // 4

        ++i;
        System.out.println(i);    // 5
        System.out.println(++i);  // 6
        System.out.println(i++);  // 6
        System.out.println(i);    // 7
    }
}

The confusion arises in the last two calls to System.out.println.

Prefix Operator:

The prefix increment operator ( ) increments the variable before using it in the operation. So, in System.out.println( i), the value of i is incremented to 6 before being printed.

Postfix Operator:

The postfix increment operator ( ) increments the variable after using it in the operation. So, in System.out.println(i ), the value of i is first printed as 6 (its current value), and then it is incremented to 7.

Example:

The following snippet illustrates the difference:

i = 5;
System.out.println(++i); // 6

This prints "6" because the prefix increment operator increments i to 6 before using it in the println function.

i = 6;
System.out.println(i++); // 6 (i = 7, prints 6)

This also prints "6" because the postfix increment operator prints the current value of i (6), then increments i to 7. The updated value of i (7) is only reflected in subsequent operations.

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