Assignment and increment

Learn =, +=, ++, -- assignment and increment operators.

Assignment and increment operators

= does assignment. Compound assignment operators like +=, -=, *=, /= combine the operation and the assignment.

int x = 10;
x += 5;  // x = x + 5  → 15
x -= 3;  // x = x - 3  → 12

++ and -- increment or decrement a variable by 1. They can come before (++x) or after (x++) the variable. Pre-increment increments then uses; post-increment uses then increments.

int x = 5;
int y = x++;  // y = 5, then x = 6
int z = ++x;  // x = 7, then z = 7

Exercise Use compound assignment

Write a Main class with a main method. Assign 10 to int total. Do total += 5 and total++. Print total with println.

Show example solution

public class Main {
    public static void main(String[] args) {
        int total = 10;
        total += 5;
        total++;
        System.out.println(total);
    }
}

Pre vs post increment

++x and x++ look the same but behave differently. ++x (pre-increment) increments then uses; x++ (post-increment) uses then increments.

int x = 5;
int a = ++x;  // x = 6, a = 6
int b = x++;  // b = 6, then x = 7

This distinction matters in loop counters and assignments. Standalone x++; or ++x; give the same result.

Test yourself

Match the assignment operators

=

Assignment
+=

Add assign
++

Increment
--

Decrement
Complete the compound assignment
```
int x = 10; x ____= 5;
```
Show answer
```
int x = 10; x += 5;
```
What is the result of int x = 5; int y = x++;?
- y = 6, x = 6
- y = 6, x = 5
- y = 5, x = 5
- y = 5, x = 6
Show answer

y = 5, x = 6 — x++ first assigns 5 to y, then makes x 6.

Next lesson: Summary - Operators

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