07-increment-decrement.md

11.16 Increment and Decrement Operators

The increment (++) and decrement (--) operators are unary operators used to increase or decrease the value of a variable by 1. They are widely used in loops and counters.

1. Pre-Increment vs Post-Increment

• Pre-Increment (++x): Increases the value before using it in the expression.
• Post-Increment (x++): Uses the current value first, then increases it.

2. Pre-Decrement vs Post-Decrement

• Pre-Decrement (--x): Decreases the value before using it.
• Post-Decrement (x--): Uses the current value first, then decreases it.

Code Example

JavaScript Code (07-inc-decr-opr.js):

// Pre Increment
// The value is incremented first, then printed.
var number = 3;
console.log(++number); // Output: 4
// verification: number is now 4

// Pre Decrement
// The value (4) is decremented first (to 3), then printed.
console.log(--number); // Output: 3


// Post Increment
// The current value (3) is printed first, then incremented to 4.
var number = 3;
console.log(number++); // Output: 3
// number is now 4

// Post Decrement
// The current value (4) is printed first, then decremented to 3.
console.log(number--); // Output: 4
// number is now 3

Quick Reference Table

Expression	Name	Action	Result (if n=3)	New Value of n
++n	Pre-increment	Add 1, then use value	4	4
n++	Post-increment	Use value, then add 1	3	4
--n	Pre-decrement	Subtract 1, then use value	2	2
n--	Post-decrement	Use value, then subtract 1	3	2