Question

我一直试图从arduino键盘读取多个字符串，但似乎第一个字符串总是附加到第二个字符串，我不知道为什么？当我打印studentNumber时，访问代码加上星号会附加到studentNumber，这可能是什么原因造成的？请帮助，非常感谢。

#include <Keypad.h>
#include <LiquidCrystal.h>
#include <Servo.h>

const byte ROWS = 4; //four rows
const byte COLS = 3; //three columns
char keys[ROWS][COLS] = {
    {'1','2','3'},
    {'4','5','6'},
    {'7','8','9'},
    {'*','0','#'}
};

byte rowPins[ROWS] = {10, 9, 8, 7}; //connect to the row pinouts of the keypad
byte colPins[COLS] = {13, 12, 11}; //connect to the column pinouts of the keypad

// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(A0, A1, A2, A3, A4, A5);
Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );
char holdKeys[] = {};
int i = 0;
int j = 0;
char accessCode[5];
char holdMaskedCode[5];
char holdMaskedNumber[8];
char studentNumber[9];
String accessCodeString;
Servo servo;


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

  servo.attach(5);
  lcd.begin(16, 4);
  lcd.setCursor(0,0);
  lcd.print("Welcome");
  lcd.setCursor(0,0);
  pinMode(4, OUTPUT);
  delay(2000);

 lcd.clear();
 lcd.print("Access Code");
  //keypad.addEventListener(getAccessCode);

}

void loop()
{
  char key = keypad.getKey();
  if(key)
  {   
    if(i < 5)
    {
      accessCode[i] = key;
      holdMaskedCode[i] = '*';
      lcd.setCursor(1,2);
      lcd.print(String(holdMaskedCode));
      if(i == 4)
      {
        lcd.clear();
        lcd.setCursor(1,2);
        accessCodeString = String(accessCode);
        lcd.clear();
        lcd.print("Student Number");
      }

      i++;
    }
    else
    {
      if(j < 9)
      {
        studentNumber[j] = key;
        holdMaskedNumber[j] = '*';
        lcd.setCursor(0,2);
        lcd.print(holdMaskedNumber);

        if(j == 8)
        {
          lcd.clear();
          String number = String(studentNumber);
          lcd.print(number);

          delay(1000);
          lcd.clear();
          for(int i =0; i<10; i++)
          {
            lcd.print("Please wait.");
            delay(500);
            lcd.clear();
            lcd.print("Please wait..");
            delay(500);
            lcd.clear();
            lcd.print("Please wait...");
            delay(500);
            lcd.clear();
          }
          digitalWrite(4, HIGH);
          for(int k =0; k<=180; k+=2)
          {   
            servo.write(k);
            delay(15);
          }
          setup();

        }

        j++;
      }

    }

  }

}

Answer 1

char accessCode[5];
...

  accessCode[i] = key;
  ....
  if(i == 4)
  {
    lcd.clear();
    lcd.setCursor(1,2);
    accessCodeString = String(accessCode);

这里不是空终止accessCode所以当你将它转换为字符串时，转换会运行到内存中，从而获取其他随机垃圾。

accessCode应该 6 字节长，在进行转换之前，请终止它，即

    accessCode[5] = 0;  // terminate string
    accessCodeString = String(accessCode);

arduino键盘如何获得多个字符串

1 个答案: