Unary Operators

1. What are Unary Operators?

Unary operators work on a single value (unlike most operators, which need two). Common examples include increment (++), decrement (--), and unary minus (-) for making a number negative.

2. Why is it used?

Unary operators are extremely common for counting purposes — like increasing a counter by 1 every time a loop runs, without writing a longer expression each time.

3. Real-Life Example

Think of a movie theatre's ticket counter that increases by one every time a new customer buys a ticket. Instead of manually recalculating, the counter simply increases by one step — just like counter++ in Java.

4. Syntax

java
a++;   // increases a by 1 (post-increment)
++a;   // increases a by 1 (pre-increment)
a--;   // decreases a by 1
-a;    // makes a value negative

5. Example Program

java
public class UnaryDemo {
    public static void main(String[] args) {
        int count = 5;
        count++;
        System.out.println("After increment: " + count);
        count--;
        System.out.println("After decrement: " + count);
    }
}

Output:

After increment: 6
After decrement: 5

6. Key Points to Remember

• a++ (post-increment) uses the current value first, then increases it; ++a (pre-increment) increases it first, then uses the new value.
• This difference between pre- and post- versions is a frequent interview question.
• Unary minus (-a) simply reverses the sign of a number.