Arduino> Structure> Boolean Operators>

!

[Boolean Operators]

Description

Logical NOT results in a true if the operand is false and vice versa.

Example Code

This operator can be used inside the condition of an if statement.

if (!x) { // if x is not true
  // statements
}

It can be used to invert the boolean value.

x = !y; // the inverted value of y is stored in x

Notes and Warnings

The bitwise not ~ (tilde) looks much different than the boolean not ! (exclamation point or "bang" as the programmers say) but you still have to be sure which one you want where.

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&&

[Boolean Operators]

Description

Logical AND results in true only if both operands are true.

Example Code

This operator can be used inside the condition of an if statement.

if (digitalRead(2) == HIGH && digitalRead(3) == HIGH) { // if BOTH the switches read HIGH
  // statements
}

Notes and Warnings

Make sure you don’t mistake the boolean AND operator, && (double ampersand) for the bitwise AND operator & (single ampersand). They are entirely different beasts.

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||

[Boolean Operators]

Description

Logical OR results in a true if either of the two operands is true.

Example Code

This operator can be used inside the condition of an if statement.

if (x > 0 || y > 0) { // if either x or y is greater than zero
  // statements
}

Notes and Warnings

Do not confuse the boolean || (double pipe) operator with the bitwise OR operator | (single pipe).

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