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— | en:reference:language:boolean [2023/06/07 04:23] (当前版本) – 外部编辑 127.0.0.1 | ||
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+ | ====== Boolean Operators ====== | ||
+ | |||
+ | |||
+ | These can be used inside the condition of an if statement. | ||
+ | ===== && (logical and) ===== | ||
+ | |||
+ | True only if both operands are true, e.g. | ||
+ | < | ||
+ | if (digitalRead(2) == HIGH && digitalRead(3) == HIGH) { // read two switches | ||
+ | // ... | ||
+ | } | ||
+ | </ | ||
+ | is true only if both inputs are high. | ||
+ | ===== || (logical or) ===== | ||
+ | |||
+ | True if either operand is true, e.g. | ||
+ | < | ||
+ | if (x > 0 || y > 0) { | ||
+ | // ... | ||
+ | } | ||
+ | </ | ||
+ | is true if either x or y is greater than 0. | ||
+ | ===== ! (not) ===== | ||
+ | |||
+ | True if the operand is false, e.g. | ||
+ | < | ||
+ | if (!x) { | ||
+ | // ... | ||
+ | } | ||
+ | </ | ||
+ | is true if x is false (i.e. if x equals 0). | ||
+ | ===== Warning ===== | ||
+ | |||
+ | Make sure you don't mistake the boolean AND operator, && (double ampersand) for the bitwise AND operator & (single ampersand). They are entirely different beasts. | ||
+ | |||
+ | |||
+ | Similarly, do not confuse the boolean || (double pipe) operator with the bitwise OR operator | (single pipe). | ||
+ | |||
+ | |||
+ | The bitwise not ~ (tilde) looks much different than the boolean not ! (exclamation point or " | ||
+ | ===== Examples ===== | ||
+ | < | ||
+ | if (a >= 10 && a <= 20){} // true if a is between 10 and 20 | ||
+ | </ | ||
+ | |||