Increment and Decrement Operator in Java

Increment and decrement operator in Java are unary operators that are used to increase or decrease the value of a variable by one. The increment operator is ++ and the decrement operator is --.

Uses of increment and decrement operator in Java

The increment operator can be used in two ways:

• Prefix: This is when the operator is placed before the variable, such as ++x. This means that the value of x is incremented first, and then the value is used in the expression.
• Postfix: This is when the operator is placed after the variable, such as x++. This means that the value of x is used in the expression first, and then the value is incremented.

The decrement operator works in the same way, but it decreases the value of the variable by one instead of increasing it.

Let’s see an example of how auto increment and auto decrement can be used in Java.

Pre Increment

Example:

public class PreIncrementExample {
    public static void main(String[] args) {
        int num = 5;

        // Pre-increment: Increment the value of 'num' by 1 before using it in an expression.
        int result = ++num;

        System.out.println("num: " + num);       // Output: num: 6
        System.out.println("result: " + result); // Output: result: 6
    }
}

In this example, the pre-increment operator ++num increments the value of num by 1 before assigning it to the result variable. As a result, both num and result become 6 after the pre-increment operation.

Post Increment

public class PostIncrementExample {
    public static void main(String[] args) {
        int num = 5;

        // Post-increment: Use the current value of 'num' in the expression and then increment it by 1.
        int result = num++;

        System.out.println("num: " + num);       // Output: num: 6
        System.out.println("result: " + result); // Output: result: 5
    }
}

In this example, the post-increment operator num++ is used in the expression, so the current value of num (which is 5) is used to assign to the result variable. After the assignment, the value of num is incremented by 1. As a result, num becomes 6, but the result variable gets the original value of num (5) before the increment.

Post Decrement

public class PostDecrementExample {
    public static void main(String[] args) {
        int num = 10;

        // Post-decrement: Use the current value of 'num' in the expression and then decrement it by 1.
        int result = num--;

        System.out.println("num: " + num);       // Output: num: 9
        System.out.println("result: " + result); // Output: result: 10
    }
}

In this example, the post-decrement operator num-- is used in the expression, so the current value of num (which is 10) is used to assign to the result variable. After the assignment, the value of num is decremented by 1. As a result, num becomes 9, but the result variable gets the original value of num (10) before the decrement.

Pre Decrement

public class PreDecrementExample {
    public static void main(String[] args) {
        int num = 10;

        // Pre-decrement: Decrement the value of 'num' by 1 before using it in an expression.
        int result = --num;

        System.out.println("num: " + num);       // Output: num: 9
        System.out.println("result: " + result); // Output: result: 9
    }
}

In this example, the pre-decrement operator --num decrements the value of num by 1 before assigning it to the result variable. As a result, both num and result become 9 after the pre-decrement operation.

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