Arduino if语句失败

if (condition) {
  // 如果条件为真，执行这里的代码
} else {
  // 如果条件为假，执行这里的代码
}

int sensorValue = analogRead(A0);
if (sensorValue > 500) {  // 假设传感器读数范围是0-1023
  digitalWrite(LED_BUILTIN, HIGH);
} else {
  digitalWrite(LED_BUILTIN, LOW);
}

int sensorValue;
sensorValue = analogRead(A0);
if (sensorValue > 500) {
  digitalWrite(LED_BUILTIN, HIGH);
} else {
  digitalWrite(LED_BUILTIN, LOW);
}

int sensorPin = A0;
int ledPin = LED_BUILTIN;
int sensorValue;

void setup() {
  pinMode(ledPin, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  sensorValue = analogRead(sensorPin);
  if (sensorValue > 500) {
    digitalWrite(ledPin, HIGH);
  } else {
    digitalWrite(ledPin, LOW);
  }
  delay(1000);
}

int sensorValue = analogRead(A0);
if (sensorValue < 500) {  // 注意这里是小于500
  digitalWrite(LED_BUILTIN, HIGH);
} else {
  digitalWrite(LED_BUILTIN, LOW);
}