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: (age >= 18) && (hasLicense) is true when both age is 18+ and a license is held. (isWeekend) || (isHoliday) is true on weekends or holidays. These operators let you build complex conditions.

Short-circuit evaluation

C++ uses short-circuit evaluation with logical operators: when the result is determined, the remaining side is not evaluated.

With &&, if the left side is false, the right side is skipped (the result is already false). With ||, if the left side is true, the right side is skipped (the result is already true).

This behavior lets you write safe conditions: (ptr != nullptr) && (ptr->value > 0). If ptr is null, the right side is never evaluated, preventing a crash. Understanding short-circuit helps you write safer code.

Exercise Print logical results

Inside main, declare bool ready = true; and bool loaded = false;. Perform two logical operations: bool canFire = ready && loaded; and bool either = ready || loaded;. Print both on separate lines with std::cout using std::endl.

Show example solution

#include <iostream>

int main() {
    // Declare ready and loaded
    // Do logical operations and print them
    bool ready = true;
    bool loaded = false;
    bool canFire = ready && loaded;
    bool either = ready || loaded;
    std::cout << canFire << std::endl;
    std::cout << either << std::endl;
    return 0;
}

Test yourself

What is the result of true && false?
- true (1)
- Undefined
- Error
- false (0)
Show answer

false (0) — && requires both sides true; if one is false the result is false.
Match logical operators

&&

And
||

Or
!

Not
short-circuit

Early exit

Logical and

bool canFire = ready ____ loaded;

Show answer

bool canFire = ready && loaded;

Next lesson: Bitwise operators

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