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標題: Arduino提示expected initializer before numeric constant [打印本頁]

作者: alan51hei 時間: 2020-7-8 15:46
標題: Arduino提示expected initializer before numeric constant
大家好，新人學(xué)習arduino。遇到了一個奇怪的問題。

提示：expected initializer before numeric constant，數(shù)值常量之前應(yīng)為初始值設(shè)定項

按我理解第一步預(yù)定義常量不就是在設(shè)定初始值嗎？附上程序和報錯信息。

請大佬指點一二。謝謝！

程序：
const int BUTTON_A  7
const int BUTTON_B  8

void setup() {
  // put your setup code here, to run once:

  pinMode(LED_BUILTIN,OUTPUT);
  pinMode(7,INPUT);
  pinMode(8,INPUT);

}

void loop() {
  // put your main code here, to run repeatedly:
if (LOW == digitalRead(BUTTON_A){
  bool FLAG_A = 1;
  unsigned long time_A_init = millis();
  }
if (FLAG_A){
  if (millis()-time_A_init > SET_A){
digitalWrite(LED_BUILTIN,HIGH);
FLAG_A = 0;
time_A_init = 0;
delay(1000);
digitalWrite(LED_BUILTIN,LOW);
  }
}
}

報錯信息
Arduino:1.8.5 (Windows 7), 開發(fā)板："Arduino/Genuino Uno"

20200708_DELAY:2: error: expected initializer before numeric constant

const int BUTTON_A  7

                  ^

D:\Alan wu\Arduino\20200708_DELAY\20200708_DELAY.ino: In function 'void loop()':

20200708_DELAY:16: error: 'BUTTON_A' was not declared in this scope

if (LOW == digitalRead(BUTTON_A){

                     ^

20200708_DELAY:16: error: expected ')' before '{' token

if (LOW == digitalRead(BUTTON_A){

                              ^

20200708_DELAY:29: error: expected primary-expression before '}' token

}

^

exit status 1
expected initializer before numeric constant

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這份報告會包含更多信息。

作者: alan51hei 時間: 2020-7-8 16:12
我嘗試將const int BUTTON_A 7 表達方式，改成 #define BUTTON_A 7

可以成功加載了。不明白是為什么？

歡迎光臨 (http://m.raoushi.com/bbs/)