Logical operators

Learn boolean logic with &&, || and !.

Logical operators

Logical operators combine bool values: && (and), || (or), ! (not).

&& gives true only when both sides are true. || gives true when at least one side is true. ! flips the value: !true = false.

Example: if (age >= 18 && hasTicket) — passes only if age is right and there is a ticket. These operators are the basic way to combine conditions.

Short-circuit evaluation

The && and || operators short-circuit: once the result is known, they skip the rest.

For example in false && expensiveCall() the left side is false, so the right side is not called; the result is false. This avoids unnecessary work.

Similarly in true || expensiveCall() the left side is true, so the right side is not called. This feature is used to safely guard side effects.

Exercise Logical operations

Write print(true && false), print(true || false) and print(!true) inside void main().

Show example solution

void main() {
  print(true && false);
  print(true || false);
  print(!true);
}

Test yourself

What is the result of true && false?
- true
- false
- 1
- Throws an error
Show answer

false — && requires both sides to be true.

And operator

if (a > 0 ____ a < 10) { print('in range'); }

Show answer

if (a > 0 && a < 10) { print('in range'); }

Logical operators

&&

And
||

Or
!

Not
true

True

Next lesson: Null-aware operators

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