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This example is for Wiring version 1.0 build 0100+. If you have a previous version, use the examples included with your software. If you see any errors or have comments, please let us know.

Logical Operators.
The logical operators for AND (&&) and OR (||) are used to combine simple relational statements into more complex expressions. The NOT (!) operator is used to negate a boolean statement.

    int RED = 8;  // red LED on digital pin 8
    int BLUE = 9;  // blue LED on digital pin 9
    boolean op = false;

    void setup()
    {
      pinMode(RED, OUTPUT);
      pinMode(BLUE, OUTPUT);
    }

    void loop()
    {
      for (int i = 5; i <= 195; i += 5)
      {
        // Logical AND
        if ((i > 35) && (i < 100))
        {
          op = false;
        }

        // Logical OR
        if ((i <= 35) || (i >= 100))
        {
          op = true;
        }

        // Testing if a boolean value is "true"
        // The expression "if (op)" is equivalent to "if (op == true)"
        if (op)
        {
          digitalWrite(RED, LOW);
          digitalWrite(BLUE, HIGH);
          delay(200);  // delay to visualize the LED change
        }

        // Testing if a boolean value is "false"
        // The expression "if (!op)" is equivalent to "if (op == false)"
        if (!op)
        {
          digitalWrite(RED, HIGH);
          digitalWrite(BLUE, LOW);
          delay(200);  // delay to visualize the LED change
        }
      }
    }